CHAP. .III. MURICID^ AND TURBINELLID^. 95 



If the reader turn to the figures of Clavalithes longcevus, 

 clavellatus, scalaris, Noce, and rvgosus*, and to that of 

 Leiostomus hulhiformis '\, he will at once perceive their 

 mutual affinity much better than from our description. 

 (83.) Having now supplied all the details in our 

 power respecting the two great families of the Zoophaga, 

 or predacious shell-fish, — and which, in fact, stand at 

 the head of the entire class of Testacea, — we shall 

 lay before our readers the following diagram, which 

 will explain, more distinctly than our usual tables^ the 

 circular affinities of each of these families, and the cor- 

 responding analogies of their sub-families. 



I MaricintB 



TurbinincB 1 



2 Cassinc&Q A <j Scolymince 2 



The analogies of the two typical sub-families (1. and 

 2.) of the circles are very remarkable. We thus find that 

 the MuricincB stand opposite to the TurhinincB, and the 

 Cassince to the ScolymincB. These resemblances repose 

 on the relative developement of that portion of the 

 shell which protects the respiratory siphon (which 

 must of course be modified in unison with its covering 

 or sheath) : thus, in the MuricincB and the Turhinince, 

 the basal canal is considerably longer than in the Cassince 

 and the Scolymmrp, where, in efffect, this part is either 

 short, or absolutely wanting. Thus it is, that we may 

 often overlook, or be ignorant of, some one character, 

 which, when discovered, serves as a common bond of 

 analogy between two groups, in all other respects to- 

 tally different. 



* Ency. M6th. \<\. 125. + Ibid. pi. 428. fig. 1. a, b. 



