Dr. J. E. Gray o?i the genus Assiminia. 



421 



pura,FascioIaria, Columbella, &c., I should not be able to distinguish 

 one from the other \nthout the examination of the teeth or the lin- 

 gual membrane, and that would only enable me to separate Triton, 

 Cassis and Fasciolaria from each other and from Murex, Purjmra and 

 Columbella, and not the three latter genera from each other; and it is 

 the same with the animals of several other orders and famihcs ; — 



Fig. 2. 



1. Truncatella ti'uncatula ^. 



a. With foot exteuded, in the act of 



drawing up the shell. 



b. Side view. 



c. Seen beneath as crawling up a 



glass, when the muzzle is ex- 

 serted. 



2. Assiminia Grayana. 



a. Under side of animal and shell. 



b. Side view. 



c. Front of foot, showing how the 



lower lamina of the foot pro- 

 jects beyond the upper. 



yet the animals of the two genera Assiminia and Truncatella (see 

 figs. 1 and 2) proposed to be united, are so imlike in general ap- 

 pearance, minute structure and habit, that it is extraordinary that 

 any person should have made the proposal. 



I think the best way to show the distinction of these two genera 

 will be to copy, in addition to the extract already given, the figures 

 (see figs. 1 and 2) and descriptions of tlie animals given in difterent 

 authors, commencing with Mr. Lowe, who has figured and described 

 the animal of Truncatella in the fifth volume of the ' Zoological 

 Journal,' and Mr. Berkeley's description and figure of the animal of 

 Assiminia ; then the description of the animal of the Indian species 

 of the latter genus, both printed in the volume above referred to ; 

 and, lastly, some extracts of additional ])eculiarity of the genus 

 Truncatella, observed by Mr. Clark, and published in his work on 

 British MoUusca. 



" 1. Truncatella. R. T. Lowe, Zool. Journ. v. 299. t. 19. f. 4. 



*' Tentuculu (2 contructilia) cylindrico-conica, brevia, obtusa, basi 

 distincta, proboscide separata; oculis sessilibus paullo supra basis 

 unguium externum posit is. Caput proboscidi/orme exsertum. Os 

 ad extremitalem proboscidis cylindricce, inter tentacula exserta, 

 disci/ormem, supra emarginatarn (sc. bilobam, ob buccas labiates in 

 proboscidem ipsam coadunatas vel commutatas). Pallium collare 

 siphone iiullo; orijicio ad dextrum corporis ut in Helicc, Melam- 

 pode, Pedipede, <51c. Pes rotundatus vel ovalis, brevis, minimus, 

 posticus. Operculum corneum simplex, i.e.non spirale, ovale, 

 aperturam testa omnino claudens. Testa turrita; adulta cylin- 



