Deep-water Limpets and Chitons. 25 
edge; no copulatory or external genital organs; mouth pro- 
vided with a horny jaw and long radula with peculiar teeth ; 
dental formula not exceeding say3} metamorphosis of the 
embryo taking place in the egg, which is fertilized in the ovary. 
Suborder ABRANCHIATA. 
Animal without external branchie. Embryonic shell spiral. 
Family Lepetide. 
Subfamily Lepetine. Without eyes; with a marginated 
muzzle extended (on each side) into a tentacular process. 
ee 1 0 
Uneini erect. Dental formula sa55 (?=s@q53)- 
Lepeta, f£ Lepeta,s.s.(+ Pilidium, Forbes non Middendorff). 
Gray Cryptobranchia, Middendortft. 
Subfamily Lepetelliine. With eyes; other soft parts as in 
Lepeta. Uncinus scale-like. Dental formula iyi ?= 
0 
1 (+3) i) : 
Lepetella, Verrill. 
Suborder PROTEOBRANCHIATA. 
Animal with external branchiea. Embryonic shell conical. 
Family Acmzide. 
With a plumose cervical branchia; with or without a 
branchial cordon ; muzzle frilled ; no rhachidian tooth. 
A. Without a cordon. 
A. Muzzle with lappets. 
a. Blind. 
Pectinodonta, Dall. sa G— Gas) 
b. With eyes. 
Scutellina, Gray. ‘Typical species not yet examined. 
Acmea, Esch. EE 
B. Without muzzle-lappets. 
Collisella, Dall, s. s. 
Collisellina, Dall. 
2 OY 
=a 
Oollisella | 
oy a ONE aah 
2 (2—1.1—2) 2° 
