188 SYSTEMATIC ARRANGEMENT 



exposed part of the valves small, subcordate, as broad as long. Gills 



1 



1. A. vestita, Adams, Gen. Moll. t. 55. f. 2. 



" The valves of Chitonellus Emersonianus are covered with a thin 

 membrane coated with a dirty scurfy epidermis, which is easily rubbed 

 off. Margin broad, thick, resembling macerated calf-skin, coated 

 like the rest of the surface, and having two ranges of small tufts of 

 yellowish hairs, two on each of the intermediate, and six or eight 

 around the terminal valves." — Gould, Moll. Mass. 152. f. 19. 



d. The mantle smooth ; pores with a tuft of small spines ; exposed 

 part of valves very small, linear. 



23. Cryptoconchtjs. 



Body oblong, rather convex. Mantle smooth ; back flattish or 

 concave in the centre ; the pores on the upper part of the sides of 

 the back, each containing a tuft of short spicula ; exposed part of 

 the valves linear, much longer than broad, the plate of insertion of 

 the front valve slightly crenated in front. Gills on the hinder half 

 of the sides of the foot. 



]. C. porosus, t. 207. f. 4, t. 208. f. 1. 



APPENDIX to ScUTIBRANCHIATA. 



At page 136, before Suborder I. Scutibranchia, add — 



Suborder I*. Pseudobranchia. 



Gills in form of branched vessel on the inner surface of the mantle. 

 Body and shell spiral. The lateral central teeth large, irregular. 

 Operculum none. Terrestrial. 



These differ from Pulmonata in the mantle being free from the 

 nape, leaving the pulmonary cavity open, and in the animal being 

 unisexual. They differ from Phaneropneumona (p. 78), with which 

 they have hitherto been united, in the teeth being truly Riphido- 

 glossal. 



Fam. I*. PROSERPINADjE (Erase from p. 86). 



Muzzle short, annulated. Tentacles lateral, subulate, short, distant. 

 Eyes sessile, on the outer side of the base of the tentacles ; sides 

 simple, without any membranaceous fringe or lateral beards. The 

 lateral central teeth large, irregular, lobed or dentated. Foot 

 moderate, truncated in front, acute and keeled above behind, with a 

 concavity in the front part for the base of the shell, lined with an 

 extension of the mantle. Operculum none. Shell spiral, depressed ; 



