REPORT ON THE PTEROPODA. 53 



these nuchal tentacles are quite separated from the so-called " tentacles." They are 

 terminated by a small swelling, and although rather short, they are more projecting than 

 in all other Gymnosomata, except Clionopsis krohni ; they are more laterally inserted 

 than in the other genera but are innervated in the same manner. 1 These tentacles are 

 shown in PI. III. figs. 7, 8. 



2. Buccal Appendages. — They number one pair, are very long (nearly as long 

 as the fins), flattened and extensible, and are inserted one on each side of the buccal 

 orifice (3, fig. 4). They are the so-called tentacles of the majority of zoologists, less 

 the " medial branch of their basis," which is, as we have seen, 

 the true anterior tentacles (2, fig. 4). Souleyet calls them 

 gills. 2 Ihering 3 is the only one who considered them as 

 corresponding to the buccal appendages of Clione, &c; but he 



did not recognise the tentacles properly so-called. (y^\J"~ 



Kegarding the union by their bases of the anterior Fl ^i/ f f ntvieffr^td^ 

 tentacles and buccal appendages, I explain it as follows. The \° ^rioT S 'teutkd^; C t wli 

 genus Halopsyche is the only one among the Gymnosomata ^ n age ' ' antenor 

 which does not possess the so-called cephalic hood, which 



covers the buccal appendages when these are retracted within the buccal cavity. The 

 buccal orifice of Halopsyche, therefore corresponds to the " false lips " of Clione ; the 

 buccal appendages indeed are inserted on its sides, like the cephaloconi in Clione. The 

 anterior tentacle not being therefore inserted on a cephalic hood in this genus, has been 

 confounded, so far as the base is concerned, with the buccal appendage, because both 

 have a common retractor muscle. 



The structure of the buccal appendages of Halopsyche is not known, and I had no 

 specimens sufficiently good for histological investigation. 



Halopsyche? Bronn. 



1825. Pysche, Rang (not Linne), Description d'un nouveau genre de la classe des Pte>opodes, 



Ann. d. Sci. Nat., ser. 1, t. v. p. 284. 

 1827. Euribia, Rang (not Hiibner, 1806), Description de deux genres nouveaux appartenant a 



la classe des Pteropodes, Ann. d. Sci. Nat., ser. 1, t. xii. p. 328. 

 1856. Euryhia, Woodward, A Manual of the Mollusca, p. 206. 



1862. Halopsyche, Bronn, Die Klassen und Ordnungen des Thierreichs, Bd. iii. p. 645. 

 1862. Theceurybia, Bronn, Die Klassen und Ordnungen des Thierreichs, Bd. iii. p. 645. 



Characters and Description the same as for the family Halopsychidse. Rang 

 established the genus Pysche in 1825 for a Pteropod without a shell that he called 



1 Pelseueer, Recherches sur le systeme nerveaux des Pteropodes, Archives de Biologie, t. vii. p. 110. 



2 Voyage de la Bonite, Zoologie, t. ii. p. 247. 



3 Vergleichende Anatomie des Nervensystems und Phylogenie der Mollusken, p. 246. 



4 From &*;, sea, and ipixh a mythological name . 



