OF MOLLUSCA. 221 



sides of the back, and continuous above in front of the head. Vent 

 central, in hinder half of the back. Genital orifice on right side. 

 Jaws plain, horny. Lingual membrane broad, with numerous series 

 of smooth spines. 



1 . P. mucroniferus, t. 1 97. f. K Forbes $■ Hartley, B.M. t. Z.Z. f. 2. 



2. P. ? pilosus (Zephrina pilosa), t. 199. f. 1. 



2. Janus. 

 Body ovate, oblong, pointed behind ; forehead with a small veil. 

 Tentacles four ; dorsal laminated, connected by an arcuated crest ; 

 oral tentacles with or without a veil. Gills ovate, on the prominent 

 edges of the back and continuous above the head. Vent central, in 

 hinder part of back. Jaws horny, denticulated ; genital orifices on 

 the right side. Lingual membrane broad, with numerous series of 

 simple spines ; central series distinct. 



1. J. Spinolse, t. 200. f. 2. Antiopa splendida, Forbes &• Hartley, 

 B.M. t. B.B.B. f. 6. 



B. Lingual membrane narrow, with a single central (or very rarely 

 two lateral) series of teeth (p. 219). 



a. Reproductive organs with a single external orifice. Liver dif- 

 fused, and a single central g astro-hepatic vessel. 



§ The posterior vessel of the gastro- hepatic system below the ovary. 



Fam. XIV. HEROID^E. 



Mantle obsolete ; frontal veil rather large, plain, produced at the 

 sides. Tentacles two, linear, simple, not retractile. Branchiae 

 branched or umbellated. Lingual membrane with a central series of 

 large denticulated spines, and two series of simple lateral teeth. 

 Jaws corneous. 



1. Hero. 



Body slender. Foot broadish. Cloak adnate. Tentacles simple, 

 unprotected, contractile. Branchiae lateral, a simple series on each 

 side, branched like a shrub ; labial veil ample, produced on both 

 sides into an oblong lobe. 



1. H. formosa. 



2. H. fimbriata. 



2. ? Gellina. 



Gill clavate, simple. Teeth ? 



1. G. affinis, t. 199. f. 9. 



