78 SHELLS AND SHELL- FISH. PART I. 



remember, at the time, being completely puzzled as to 

 what genus it should be placed in, This, of course, 

 was when we were entirely ignorant of those prin- 

 ciples of variation in the Mollusca here developed; 

 but we made a memorandum of the occurrence at the 

 time, conjecturing that it might hereafter be useful. 

 Such we now think it, inasmuch as it realises the very 

 form which is requisite to complete the circle we are 

 now upon. Finally, the long spire of Clavalithes is 

 continued to Turbinella Scolymus *, which differs only 

 in this respect from T. rapa.^ 



{6S.) The Scolymina, as already remarked, are 

 rough, blunt-spined shells, having the aspect of many 

 of the Linnaean murexes : but'the canal, although short, 

 is straight; the pillar is furnished with distinct plaits, 

 generally central ; while the spire is always pointed. 

 The animal we can fortunately describe from the un- 

 published drawings of our late friend Guilding : the 

 foot of Scolymus is a little longer than the aperture, the 

 the breadth measuring one half the length ; the oper- 

 culum semicircular, and tolerably large, as in Fascio- 

 laria; the peduncles of the eyes very long, the eyes 

 themselves being placed more than half way from the 

 base to the tip ; the anterior part of the foot is truncate, 

 with the angles rounded; the hinder part is also rounded ; 

 the mouth is not probosciform ; and the respiratory 

 siphon is rather short. We cannot make use of this 

 information to the extent that could be wished ; but it 

 will become doubly valuable for comparison, so soon as 

 the animals of Turbinella and of the neighbouring 

 genera are made known. The first form which pre- 

 sents itself in this division, after leaving Fasciolaria, is 

 our genus Plicatella, an extensive group of small shells 

 hitherto confounded with Fasciolaria and Scolymus. 

 From the first, they are known by the little plaits upon 

 the pillar being almost transverse (as in Scolymus), and 

 not oblique, as in Fasciolaria; these plaits are likewise 



* Ency. Meth. pi. 431. bis, fig. 2. t Ibid. fig. 1. 



