of P. J. \\x Beneden'), Souleyet"), Gegenbaur''), Boas *) and Pelseneer"), it seems to me of no 

 use to discuss the anatom\- fvilly, as the various researches, which com]jlete each otlier, have 

 been already sufficiently treated b)- Pelseneer, who at the same time demonstrated the 

 phvlooenetic affinities of the subgenera. 



Crcsris shows much resemblance with Liiiiacimi and is tlie most primitive subgenus of 

 Clio. This is not only shown by the tentacular lobe on the fin, with which also some species 

 of Limacina are provided, but also b)- the tentacles, the left of which is ver)- small and scarcely 

 visible, which agrees with the one that is found in Limacina. The left tentacle is somewhat 

 larger in Hyalocylix^ Styliola and Clio (s. str.) but even in this last subgenus it does not nearly 

 attain the dimensions of the right one. I must observe, however, that I could only study two 

 species of Clio (s. str.)^ so that m\- researches are not complete in this respect. Clio pyraiiiidata 

 and Clio C2ispidata (Le)'den Museum) were only at my disposal. In this two species I remarked 

 between the tentacles a triangular lobe, directed forward ; it has been already noted by Souleyet. 



As to the foot, the fins, the mantle and the pallial gland, I entirely refer to Pelseneer. 

 Also with regard to the jaws, the radula, and the salivary glands. 



In all the species of the genus CV/ö, examined by me, I found a caecum, entirely 

 concealed in the liver, and opening at the right side of the stomach. In Clio (s. str.) it is 

 somewhat swoUen at the end. In Clio ciispidata I noticed a curious, bell-shaped organ, strongly 

 attached to the intestine. Muscular fibres were seen on this bell, and, comparable with a 

 dapper, a dark, rounded organ was found within. The bad preservation of the specimens did 

 not allow me to study the structure of this organ ; most probably it is glandular and opens into 

 the intestine (PI. I, fig. i8). 



About the flexure of the intestine, the position of the anus in the various subgenera, 

 and the anal gland, I have nothing to remark. Gegenbaur's figure ") which represents the 

 intestine of Clio (Crescis) acicula as curved dorsally, has been reproduced in several works, 

 but the inaccuracies as to the organisation of this species were carried to the extreme by 

 Haller "), whose figure is wrong in almost every respect. Hornell's paper "), treating on Clio 

 (Creseis) acicula^ I could unfortunately not study. 



The various dispositions of the heart and kidney have been described by Boas °) ; 

 I, therefore, refer to his work. Gills are entirely wanting. 



The gonad is situated posteriorly ; in Clio ciispidata, however, I have always found it 

 dorsally to the liver, and somewhat to the right. The duet e.xhibits an elongated swelling, but 

 its shape varies in the same species, the swelling being more or less pronounced and sometimes 

 divided into two parts, which is due in all probability to the maturation of the sexual products. 



i) Exercices zoötomiques, Mem. Acad. Sci. Brux. vol. XII, 1839. 



2) Voyage de la Bonite, Zoölogie, vol. II, p. 164 — 175. 



3) Unters. üb. Pterop. u. Heterop., Leipzig, 1S85. 



4) Spolia atlantica, p. 54 — 57. 



5) Chall. Rep. LXVI, p. 13—16. 



6) Unters. üb. Pterop. u. Heterop., pi. II, fig. i. 



7) Lehrb. vergl. Anat. p. 261, 1902. 



S) .\natomical Description of C-ijv/j-, as a typical Pteropod, Marine Zool., vol. 11, (1S95), p. 19 — 24. 

 9) Spolia atlantica, p. 28 — 30. 



