200 Mr. W. S. MacLeay on the Dying Struggle 



were porphyritic, with large crystals of felspar, and others 

 looked like pitchstone, with a mixture of pumice ; but from its 

 not breaking in a conchoidal form, I am inclined to think it is 

 an obsidian that has suddenly cooled. 



[To be continued.] 



XXXII. On the Dying Struggle of the Dichotomous System. 

 By W. S. MacLeay, Esq. M.A. F.L.S. In a Letter to 

 N. A. Vigors, Esq. F.R.S. 



[Concluded from p. 140.] 

 "PJR. FLEMING'S late work on British Animals I repeat 

 -*-* that I have never seen ; but his series of affinity as given 

 in the " Philosophy of Zoology" is as follows : 



Vertebrata. 



Cephalopoda. 



Mollusca. 



Tunicata. 



Annulosa. 



Cirripeda. 



Annelida. 



Entozoa. 



Radiata. 



Acrita. 

 In the Hone Entomologies, however, I have not merely 

 said, but I have proved to demonstration, that by the admis- 

 sion of the Mollusca to a higher rank than the Annulosa, the 

 latter would be so far separated from the Vertebrata as to oc- 

 casion an unnatural interruption of the series. Dr. Fleming 

 now says that the degradation of the Mollusca is decreed by 

 me, " although not very logically" in these terms ; " It follows 

 therefore that though they undoubtedly possess a very com- 

 plete system of respiration and circulation, the Mollusca are in- 

 ferior in the scale of nature to the Annulosa." These are in- 

 deed my words ; but the Doctor took good care not to cite 

 the passage which they follow, because that would have proved 

 the deduction to be strictly logical. He appears to fancy, that, 

 on account of their system of respiration and circulation, the 

 Mollusca are superior to the Annulosa; in other words, that an 

 ascidia and an oyster are superior animals to the bee and the 

 ant ! But Annulosa breathe as well or better than any Mollusca, 

 and in my present opinion, founded on late dissections, possess 

 a circulation, although of a most peculiar kind. But if they had 

 no system of circulation whatever, the place assigned by me 

 to the bee would not be altered, as Dr. Fleming would have 



himself 



