76 DR. T. ALCOCK ON THE 



belonging to each of the main divisions or orders. This I 

 have shown, so far as my present materials will admit, is 

 really the case ; and my illustrations at the same time 

 point out that Cuvier's order Cyclobranchiata must be 

 reestablished as distinct, and not included, as it is by our 

 latest authorities. Gray and Adams, in the order Scuti- 

 branchiata, to which, on the evidence of the teeth, it 

 cannot possibly be related ; and 1 may remark that, judging 

 from the specimens of each order which I have had the 

 opportunity of examining, they are equally distinct in 

 their general anatomy. 



I do not intend, on the present occasion, to go much 

 into the details of lingual dentition; but there are one or 

 two points regarding some of the animals of the order 

 Pectinibranchiata which I will take this opportunity of 

 mentioning, Fusus antiquus and Buccinum undatum are 

 animals of diflPerent genera, but both are known under the 

 common name of Whelks. Gray says, "The teeth of 

 these two genera have been exhibited and sold in London 

 as the teeth of the two sexes of Buccinum undatumj'^ the 

 difference between the two being that in Fusus the cen- 

 tral teeth have three points, while in Buccinum they have 

 seven. Whelks' palates, as they are called, are, you know, 

 very common microscopic objects; and on looking over 

 those in the cabinets of my friends, I have found tongues 

 of at least three different genera, all going under this 

 name. 



As to difference in the teeth on account of sex. Wood- 

 ward remarks, on the authority of Mr. Wilton, that in 

 Buccinum limbosum the male has seven points to the cen- 

 tral teeth, while the female has only six ; and, thinking it 

 might be interesting to make some observations on the 

 subject with regard to our common species the Buccinum 

 undatum, I took four specimens, two males and two females, 

 and mounted their tongues, as you will see. The result is 



