EANDLES: ANATOMY OF TUKRITELLA COMMUNIS. 61 



: presence of cilia. It may be that the absence of definite ciliation is 

 ' due to imperfect preservation of the specimens, though the invariable 

 ; presence of ciliated cells in the intestine, and the few that do occur in 

 the groove, would seem to refute this suggestion. 1 



The presence of a spermatic groove is characteristic of many male 

 Gastropods, e.g. Naticid.96, Cypraeidae, Strombidae, etc. In these forms 

 f a penis is present, and the furrow, which is ciliated, leads directly 

 • from the aperture of the vas-deferens in the mantle-cavity to the penis. 

 < In Spekia, Faunus, and Littorina the structure is overhung by a flap 

 [ or ridge [Moore, 7] (p. 171, pi. xv, figs. 1 and 11) ; in the latter form, 

 C and also in S trombus, a vestigial groove can be traced in the female. 



Moore [7] (pp. 160 et seq., pi. xiv, figs. 10, 13) has described 

 i a remarkable structure in connection with the female genital organs 

 5 of Tanganyicia rufofilosa and Melania episcopal is, Led. From the 

 aperture of the oviduct a well-marked furrow runs forward on the 

 k right side of the body, and terminates in a little pit beneath the eye ; 

 this pit communicates with a brood -pouch, situated on the left side 

 '•■ behind and below the tentacle in Tanganyicia rufofilosa, median and 

 1 above the oesophagus in Melania episcopalis, Led. The furrow occupies 

 > the same position as does the spermatic groove in the male. 



We have thus evidence of a genital groove occurring in both sexes 

 : of certain Gastropods. In all these forms the furrow has a definite 

 1 connection with the genital aperture, and does not extend bej'ond it, 

 whereas in Turrit ella the genital aperture is situated very far forward 

 ' in the mantle-cavity, and, though it is placed just above the groove, 

 I yet has no such intimate connection with it as exists in any of the 

 other aforementioned Gastropods. Moreover, the structure extends 

 ' far beyond the genital aperture, to the extreme posterior end of the 



mantle-cavity. 



! There is no structure in Littorina, Faunus, etc., comparable to the 



i well-marked extension of the groove which exists in Turritella, so 



that the homology of this structure is doubtful. The anterior portion 



and genital flap (PL VI, Pig. 1, g.f.) may, and in all probability do, 



correspond to the genital groove of Littorina, etc., but it is difficult to 



! say what the remaining posterior portion can represent. 



The excretory organ is fairly large, consisting of a characteristic 

 1 spongy tissue (PL VI, Pig. 6, k) ; it opens directly into the mantle- 

 cavity by means of a pore (Ic.o.), there being no long ureter. A reno- 

 pericardial canal (r.p.c.) is present, placing the kidney in communication 

 with the pericardium. 



The heart and pericardium are those of a typical monotocardian. 

 The ventricle gives origin to a common aorta, which almost immediately 

 divides into anterior and posterior branches. 



1 Since the above was written, I have received living specimens of T. communis, 

 Risso, i'rorn Mr. E. W. L. Holt. Some of these were carefully fixed with 

 corrosive sublimate in acetic acid, and an examination of transverse sections 

 revealed the presence of definite ciliation of the epithelium of the genital groove. 

 There appeared to be a special concentration of cilia near the apex of the outer 

 ridge. 



