THE NAUTILUS. 47 



" Finally we turn to the Amphineura. Here from Dr. Pilsbry's 

 work we get : Polyplacophora, 540 : Aplacophora, 33. Adding from 

 the Zool. Record in a precisely similar manner we have to include 

 Polyplacophora, 59 ; Aplacophora, 4 ; and we get a final total of 636. 



" The next question which arises is, how far are the above totals 

 trustworthy ? On the one hand they are inflated by a mass of 

 synonyms which still masquerade as species, while on the other hand 

 they are reduced by a certain number of omissions. The only 

 omission of any importance, however, will, I think, be found in the 

 Nudibranchiata, of which the true total is, owing to the nature of the 

 works consulted, unduly curtailed." 



" Making a reduction therefore for synonyms and allowing for the 

 above, I think a very fair approximation will be : Cephalopoda, 450; 

 Gastropoda, 40,000 ; Scaphopoda, 220 ; Pelecypoda, 8,500 ; Amphi- 

 neura, 600 ; or a grand total of 49,770 — say 50,000 known species 

 of recent mollusca." C. W. J. 



The Locality of Sax's Type of Alasmidonta marginata. 

 — Bearing on the question whether the name Alasmidonta marginata 

 of Say should be applied to an Eastern or a Western shell, and as it 

 has been questioned that Lea ever collected in the Scioto River, the 

 following quotation l will be found of interest : " Mr. Lea remembers 

 that Mr. Say founded his genus Alasmodonta on a single valve which 

 he himself had picked up on the river shore at Chillicothe, Ohio, and 

 which he carried from that place to Philadelphia in his saddle-bags." 



From this it is clear that Say's name should be applied to the form 

 known as A. trvncata of the western states, as it corroborates Say's 

 statement that the type was found in the Scioto River. 



It may be well to point out that the Journal of the Academy of 

 Natural Sciences of Philadelphia, containing the description of Alas- 

 midonta marginata, although dated December, 1818, really did not 

 appear until the year 1819, which is the same date as the separate 

 of Say's paper from the 3d edition of Nicholson's Encyclopedia. 

 From the fact that no locality for the species is given in the latter 

 paper, it seems safe to say that A. marginata was first described 

 therein, the locality being supplied in the later paper in the Journal, 

 which was published prior to March 13th, 1819, as Say, in a letter 

 of that date, speaks of having sent a copy of it to a correspondent. 



In Say's American Conchology there is an article, or chapter per- 

 haps, entitled : " An attempt to exhibit a synonymy of the Western 

 North American species of the genera Unio and Alasmodonta," in 

 which will be found listed as a western species, "Alasmodonta mar- 

 ginata Say." — William J. Fox. 



1 From The Published Writings of Isaac Lea, LL. D., by Newton Pratt Scud- 

 der. (Bull. No. 23, W. S. Nat. Mm.) 



