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cavity resemble the adaptation in air-breading prosobranchs as, e.g., Helicina (Neritimorpha) and Cyclophoridae (Architaenioglossa) (person, obs.). Transverse vessels between the gili and the rectum are also elear in Campanile.

Hypobranchial gland

46.    Aspect: 0= thick, with chambers; 1= thin,

smooth, solid (all taxa except M. modulus) (CI= 100, Rl= 100).

The hypobranchial gland with several inner chambers and folds is the normal condition in vetigastropods and littorinids, this condition occurs among cerithioideans only in Modulus. lt is regarded here as the plesiomorphic State. In the remainder of the examined species the hypobranchial gland is a thin, homogeneous glandular layer, even in Campanile. In this species, however, some specimens (but not all) develop a tali glandular fold of homogeneous glandular tissue (fig. 412).

Adrectal sinus

47.    Type: 0= inconspicuous; 1=veiy broad, associated

with the kidney lobe (thiarids); 2= very broad, associated with large nephrostome (pleurocerids) (CI= 100, Rl= 100, not additive). The adrectal sinus is generally inconspicuous, but in some cerithioideans it is well developed, becoming a iarge chamber where the rectum runs free. This condition, regarded as apomorphic, occurs in the freshwater thiarids and pleurocerids andisabsent in remainder ingroup species and also in all outgroups. The relationship between the adrectal sinus and the kidney, however, differs in both families as above explained.

Rectum

48.    Width: 0= medium (about 1/8 of pallial cavity

width); 1= wide (about 1/4 of pallial width) (all cerithioideans except the following); 2= narrow (Bittium varium, Finella dubia, Alaba inceria) (about 1/16 of pallial width) (CI= 100, Rl= 100, additive).

49.    Fecal pellets: 0= aligned; 1 - obliąue/compacted

(all cerithioideans except Finella dubia and

Campanile symbolicum) (Cl= 33, Rl= 66).

50.    Inner surface: 0= smooth; 1= oblique folds

(Aylacostoma exoplicata) (Cl= 100, RI= 100).

51.    Anus site: 0= near mantle border; 1= far firom

mantle border (all cerithioideans except thiarids and pleurocerids) (CI= 25, Rl= 72). The rectum of the cerithioideans is characteristically very wide, this State is different from those of the examined outgroups, it is regarded as apomorphic. The miniaturized forms (Bittium, Finella and Alaba), however, present a narrow rectum, apparently due to reversal. The wide rectum generally contains great quantities of fecal pellets obliąuely compacted, a condition not observed in the examined outgroups and regarded also as apomorphic (see Bandel, 1974 for morę comments). There are two exceptions, in Campanile and Finella the fecal pellets are aligned longitudinally. The anus of all examined cerithioideans is siphoned, i.e., preceded by a part of the rectum detached firom the mantle. Obsemtion of live specimens shows that the siphoned anus appears to be an adaptation for approaching it to mantle border during evacuation, with subseąuent retraction. Siphoned anus is also found in vetigastropods (e.g., Haliotis) and littorinids, and could be plesiomorphic.

Kidney

52.    Lobes: 0= single; 1= two, anterior lobe in

mantle roof (Melanoides tuberculatus); 2= two, anterior lobe attached to rectum, anterior lobe mostly solid (Aylacostoma tenuilabris)\ 3= same, with anterior lobe mostly hollow (Aylacostoma exoplicata, A. ci) (CI= 100, RI= 100, additive).

53.    Tissue arrangement: 0= solid; 1 = hollow, with

two chambers (thiarids); 2- hollow, with single chamber (pleurocerids); 3= very large and complex (Campanile symbolicum) (CI= 100, RI= 100, not additive).

54.    Length: 0= less than 1/4 whorl; 1= morę than

1/4 whorl, double lobed (thiarids); 2= morę than 1/4 whorl, single lobed (pleurocerids); 3= morę than 1/2 whorl (Campanile symbolicum) (Cl= 100, RI= 100, not additive).