Mr. T. D. A. Cockerell's yoles on Slugs. 99 



3. Mantle still moi"e developed and more or less coveriug shell behind. 



a. Ameiicaa vii. VeUfera, W. G. Binn. ( V. Gabhi, W. 



Ct. Binu.) 



b. Asiatic viii. Austenia, sect. Cryptausteniae. {A. 



jjlanospira, Bs.) 



B. Shell more or less whorled, but uot truly Vitrinoid ; whorls subrudi- 

 mentary, 



1 . Spii'al whorl complete below or not presenting the appearance of 



a smaller sheU within a larger. Asiatic. 



a. SheU mostly exposed. 



a\ SheU well formed, ix. AKstema,Nev. {A. gigas,'Bs.) 



a'. SheU horny x. Ibyciis (Heyn.), G.-A. {I. Jissidens, 



Heyn., /. sikimensis, G.-A.) 



b. Shell exposed only by an aperture in mantle, resembling that of 



Amtenia xi. Ibi/cus, sect. Cryptibyci. (/. magnificuSf 



G.-A., sp.) 



2. Spire presenting the appearance of a small shell within a larger. 



a. SheU exposed only by an aperture in mantle. Australian. 



xii. Pannacochlea, E. A. Smith. (P. Fis- 

 cheri, Smith.) 



6. Shell mostly exposed. Asiatic. 



xiii. Africarion, sect. Pseudaustenise. {A. 

 atei; G.-A.) 



3. SheU external, mytiUform. African. 



xiii a. Estria, Poirier. (^E. Alhiaudi, Poir.) 



C. SheU slug-like, hardly or uot at all whorled. 



1. Shell external, mytiliform. African. 



xiv. Aspidelus, Morelet. {A. Chaperi, 'Morel.) 



2, Shell exposed by a hole in the mantle only or entirely covered. 



a. Shell homy, exposed by a rather large aperture. Asiatic. 



XV. Girasia, Gray. ((?. Hooker i, Gray.) 



b. Shell oval, rudimentary, covered, animal like Girasia. Asiatic. 



xvi, Girasia, sect. Cryptogirasise. {G, ru- 

 brum, G.-A.) 



c. Shell entirely concealed or exposed only by a very minute hole ; 



mantle with pale ridges ; dentition differing from Girasia. 



Asiatic xvii. Mariaella, Gray. {M. Dussumieri, 



Val. MS., Gray.) 



d. Shell exposed by a small aperture or none ; body more or less 



keeled. African. (Urocyclidse, Simroth.) 



d\ Mantle reticulate, perforate ; body without lateral ridges. 



xviii. Uroci/chis, Gray. (U. Kirkii, Gray.) 



d*. Mantle not reticulate, hardly or not perforate ; body without 

 lateral ridges ; penis-retractor muscles several. 



xix. E/isa, Heyn. (-E". bella, Heyn.,= /on^i- 

 cauda, Fisch.) 



7* 



