ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 367 



close allies of the Cephalopoda ; he looks upon them rather as closer 

 to the Gastropoda, and thinks that the most primitive Pteropods are 

 those that are asymmetrical externally, the bilateral symmetry of a 

 number of forms being due to their pelagic mode of life ; other resem- 

 blances to the Cephalopoda are of an atavistic nature. 



In conclusion, the question whether the Mollusca are " Pseudo- 

 coelia " or " Enterocoelia " is answered in favour of the latter vievs^. 



Procalistes : a young Cephalopod •with Pedunculate Eyes.* — 

 Procalistes Suhmii, which Prof. E. Eay Lankester describes and figures, 

 is a young cephalopod with pedunculate eyes, whose general aspect 

 closely resembles a clionid pteropod, for which, indeed, the late S. 

 von Suhm, in his preliminary investigation of a living specimen, mis- 

 took it. The genus is similar to Oranchia, excepting that the eyes are 

 pedunculate, that the shorter perioral arms are aborted, and that the 

 longer (so-called prehensile) arms are devoid of suckers. In the 

 youngest stage observed there are two rows of suckers on the long 

 arms and six isolated and pedunculate suckers surrounding the mouth, 

 which appear to represent the shorter arms of other cephalopods. 



Gill in some Forms of Prosobranchiate Mollusca.| — H. L. 

 Osborn describes the gill-structure of several genera (^Chiton, Fissu- 

 rella, Fulgur, Sigaretus, Crepidula, &c.) of Prosobranchiate Mollusca. 



In Chiton and in Fissurella the gills are leafy blades attached to a 

 rachis and joined to the body only for a short distance, the base of 

 this rachis ; in the prosobranchs generally the gill consists of inde- 

 pendent plates, each one attached to the roof of the mantle cavity, 

 and not placed upon a stalk and borne free from the mantle wall. 

 The few forms which are divergent from this plan of structure are 

 readily seen to be only secondarily different from it. 



The author briefly summarizes the results of his studies as 

 follows : — The gill of Chiton and Fissurella is closely like the cteni- 

 dium, which Lankester considers the primitive type of moUuscan 

 gill. In ctenobranchs, almost universally, the gill is not a ctenidium, 

 but a very much simpler organ. Its form compares closely with the 

 gill which we have come to regard as the primitive lamellibranch 

 gill. Incomplete study of ctenobranchs and ignorance of the history 

 of the development of the ctenidia in Chiton and Fissurella prevent 

 more than a conjectural conclusion. It does not seem, however safe 

 to accept the conclusions of Spengel and Lankester that the cteno- 

 branch gill is derived from a feather-form gill like that of Fissurella 

 by the fusion of one side with the body- wall. 



Kidney of Aplysia.| — J. T. Cunningham has recently cleared up 

 the confusion that exists as to the position and relations of the renal 

 organ in Aplysia. This organ — the "triangular gland'' of Delle 

 Chiage — is situated beneath the shell and behind the pericardial 

 cavity; the reno-pericardial opening was demonstrated by injecting 

 the pericardium with Berlin blue and cutting the kidney into a series 



* Quart. Joiu-n. Micr. Sci., xxiv. (1884) pp. 311-8 (2 figs.). 



t Stud. Biol. Lab. Johns Hopkins Univ., iii. (1884) pp. 37-48 (3 pis ) 



$ MT. Zool. Stat. Neapel, iv. (1883) pp. 420-S (1 pi.). 



