OF CONCHO LOGY. 193 



Furthermore, in regard to the identity of his G. radiata with 

 stellata of Sowerby, I have not only confirmed it by the examin- 

 ation of a series of specimens from all parts of the coast, and 

 others named from the types in Mus. Cuming, but I have the 

 complete concurrence of Dr. Carpenter in the identification, and 

 no one will dispute his ability to judge in such a question. I 

 would also inquire what is the essential difference between "re 

 ticulation" and "radiating ribs" crossed by " concentric lines 

 of growth." 



Far from considering it safest to keep things separated in the 

 absence of differential characters, until they are shown to be 

 identical, I am of the opinion that it is safest not to separate 

 them until they are shown to be different. 



It is extraordinary that Dr. Cooper should have found any- 

 thing in my description of the animal, or in my alluding to the 

 auriculate anterior extensions of the muzzle as " ears," to im- 

 press him with the idea that I considered them to be auditory 

 organs. 



It seems hardly necessary to state that I used the term in a 

 colloquial sense, as "foot," "umbilicus," and other terms are 

 constantly used in descriptions of mollusks. As to the possibility 

 of the young (not embryonic) animal being branchiate and the 

 adult pulmonate, no such case is known in the whole sub-kingdom 

 of mollusca, and I prefer to await a more rational explanation 

 of the fact that young specimens may have been found in deep 

 water. 



Furthermore, I may add, that information kindly communi- 

 cated to me by Mr. J. Gwynn Jeffreys, F.R.S., confirms the iden- 

 tityin habits of the Mediterranean and Californian forms. There 

 seems to be little doubt that the Q-. Grarnoti is the Patella mam- 

 millaris, of Linnaeus, and the name should therefore be corrected 

 to read Gradinia mam miliar is, L. sp. 



