"""ifiw"'] PROCEEDINGS OF TFIE NATIONAL I\I(TSEUM. 217 



given by Conrad are, "length and height three fifths of an inch, thick- 

 ness two-fifths of an inch." The figures (PI. IS, Figs. 12, 12a, atlas) 

 show only the exterior of the specimen, and are about the same in size 

 and other respects as that of G. occidentalism before mentioned, so that 

 while Carpenter's inclusion of these imperfectly described fossils as 

 synonyms of &ormZis may be right, it will be seen from what I have stated 

 as the result of my search and examination of Conrad's description, such 

 an association of these specific names is altogether presumptive and 

 simple guess-work.* It will be seen also, upon recurring to my first 

 quotation from Dr. Carpenter, that he regarded ventricosa as a local 

 variety of horcalis, but a comparison of the hinge characters as shown 

 in the figures is sufficient to settle the question. The cardinal tooth 

 in ventricosa (left valve) as figured, it will be seen, is short and curved 

 towards the lunule, while in horealis it is triangular, obtusely wedge- 

 shaped and grooved, hinting at cleavage or forking, as previously indi- 

 cated. p]xamples varying in size from 37™'" from beaks to ventral mar- 

 gin, and 37.50'"'" in the opposite direction, to those measuring 11.50"^'" 

 from beaks to ventral niargin, and 11.25""" in the other direction, exhibit 

 this character, the larger individual (Museum No. 74194) being from the 

 neighborhood of the Aleutian Islands, Alaska, and the smaller (Museum 

 No. 73455) from 30 fiithoms near Cataliua Island, in the Santa Barbara 

 channel. The identity of the latter is further confirmed by Dr. Car- 

 penter's initials on the label. 



Genns MIODON Cpr. 



Miodou prolongatus Cpr. 



Plato XVI, Figs. 7, 9. 



This subgenus and species were described by Philip Carpenter in the 

 Annals and Magazine of Natural History (third series), Vol. xia^, De- 

 cember, 1864, p. 424. The author made this subgeneric term to cover 

 and include, as he says, certain "species intermediate in character be- 

 tween Astarte, Venericardia and Lucina. It first appears in the great 

 Oolite, where it is represented by Astarte (Miodon) orbicularis J. Sby., 

 Min. Conch., PI, 444, Figs. 2, 3. This must not be confounded with a 

 second and true Astarte orbicularis by the same author, PI. 520, Fig 2. 

 It appears in Mr. Searles Wood's Crag-series as Astarte corbis.-'' 



The form described by Carpenter as above is the only recent species 

 known. 



Several specimens are contained in the National collection, including 

 No. 15742, from Neeah Bay, and Mr. Dall obtained several examples in 

 the Alaskan region at Middleton island. 



*6abb (Paleont. Cal. ii, p. 100) unites nuder the name of C. ventricosa Gld. the 

 subtenta and occidentalis of Conrad and his own C. monilicoata. The very imperfect 

 types of the fossils in the U. S. Nat. Museum indicate that this may be a correct con- 

 clusion, though all that we can positively assert in regard to the fossils is that they 

 are certainly not C. horealis. 



