GASTROPODA 515 



a. External shell absent; slugs. 



bi Animals marine 1. Onchidhdae 



6, Land animals. 

 Ci Mantle confined to forward part of body. 



di Body with a mid-dorsal keel ; jaw smooth 12. Limacidae 



dj No keel or an indistinct one ; jaw ribbed 13, Arionidae 



c. Mantle covers entire back 14. Piiilomyciuae 



Family 1. ONCHIDHDAE. 



Shell wanting; body ovoid, with no tentacles but with the eyes at 

 the tips of a pair of stalks; mantle entirely covers the back; respiratory, 

 anal, renal, and female genital pores at the hinder end of the body; male 

 pore below the right eye stalk : 3 genera and species, which live mostly in 

 shallow^ water along the seashore in wann countries, 2 on the Pacific coast. 



Onchidella Gray. With the characters iiiven above. 



0. carpenteri Binney. Body oblong with rounded extremities and 

 sides, and gray in color; no jaw; 5 mm. long and 3 mm. broad: Puget 

 Sound to Gulf of California. 



Family 2. PUPILLIDAE.* 



Small, often minute snails, with a more or less cylindrical or conical, 

 blunt, multispiral shell; aperture small, usually contracted by internal 

 teeth or lamellae; jaw smooth or finely striate, sometimes with acces- 

 sory plate; umbilicus open; ureter straight: cosmopolitan; over 1,000 

 species, which live under or in decaying wood or leaves, usually in 

 moist places; 50 American species. 



Key to the genera of Pupillidae here described : 



a. Shells pupiform (Fig. 788). 

 hi Aperture without teeth, or with but 1 or 2. 



Ci Shell cylindrical 1. Pupilla 



Ca Shell elongate and tapering 2. Pupoides 



6a Aperture with teeth. 

 Ci Outer lip regularly rounded ; 4 tentacles. 



d, No tooth on columella 1. Plpilla 



dz One or more teeth on columella 3. Bifidarta 



Ca Outer lip indented above the middle : 2 tentacles 4. Vertigo 



aa Shell heliciform (Fig. 772) ? 5. Strobilops 



1. Pupilla Leach. Shell minute, with impressed sutures, horn- 

 eolor, and smooth; aperture with no teeth or with but 1 or 2 small 

 ones and with an expanded and reflected lip; Avhorls 5 to 9; posterior 



Achatinella," by H. A. Pilsbry, Proc. Acad. Nat. Sci., Vol. 52, p. 561, 1900. 

 "Molluska of Michigan, Part 1, Terrestrial Pulmonata," by Bryant Walker, Rep. 

 Geol. Sur., Mich., for 1905, p. 431. 



• See "A Partial Revision of the Pupae of the United States," by H. A. Pilsbry 

 and E. G. Vanatta, Proc. Acad. Nat. Sci., Phila., Vol. 52, p. 582, 1900. 



