MUSEUM OF COMPAKATIVE ZOOLOGY. 121. 



Station 33, 1568 fms., living; Station 19, 31-0 fms; Cape San Antonio, 

 1002 inis. 



This is one of the most interesting of the Arcidce obtained by the expedition. 

 The type of the genus (Lycett, 1845) is a fossil of the lower Oolite, but there 

 seems no reason for separating the recent shell from it generically or sectionally. 



Area pectunculoid.es Scacchi, var. orbiculata. 



A. pcctvnculoides ScACCHi, Notizie, etc., p. 25, Tab. I. fig. 12, 1833. 



Sigsbee, off Havana, 480 fms ; station 33, 1568 fms. 



The specimen from deeper water was nearly round, except for the slightly 

 auriculated cardinal margin ; the teeth were also proportionally more distant 

 and less strong, the exterior nearly smooth. I suspect it to be diflerent, but 

 until further material be available, refer it to this species as a variety orhiculata. 

 I can only account for Prof. Verrill's suggestion that this species and Area 

 glacialis are the same, and that Sars' figure of the variety septentrionalis repre- 

 sents a deformed specimen,* by the supposition that the Professor had no speci- 

 mens of the genuine A. glacialis for reference. It appears to nie not only that 

 they are very distinct, but that many authors would be tempted to put them in 

 different sections of the genus. Apropos of this, the reference of these small 

 species to CucuUcea by Dr. Jeffreys will hardly be accepted in view of the char- 

 acters of the type of Lamarck's genus, which materially differ from those of the 

 forms now under consideration. In this species sometimes the radiating sculp- 

 ture almost fails, at other times is very strong ; the margin is sometimes lightly 

 notched on the edge, but is smooth within the edge ; in the middle of the hinge 

 margin is an edentulous space, and all the teeth are more or less oblicj^ue. 



Area glomertila n. s. 



Shell similar in general shape, size, and sculpture to A. 'pectunculoicUs, but 

 shorter and higher, with a perfectly different hinge, and bearing much the 

 same relation to that species tliat Limopsis mimtta does to L. aurita. The ex- 

 ternal concentric sculpture is the most enduring, and is always preserved, while 

 the radiating sculpture, sometimes strong, is often evanescent ; the radiating 

 sculpture always appears inside the shell within the margin (which is smooth 

 and polished) in a series of small ridges, generally with the same level as the 

 rest of the interi(n', but sometimes rising into little tubercles, and separated by 

 rather deep, short, narrow depressions, which do not extend far inward nor 

 over the smooth margin ; liinge straight, with from fifteen to seventeen stout 

 nearly vertical teeth, usually in a continuous series ; an occasional specimen 

 shows a gap in the middle through the atrophy of one of the small central 

 teeth ; those at the ends of the series are oblique, as usual, but the series itself 

 forms a straight line. In A. pedunculoides, on the contrary, all the teeth are 



* Proc. U. S. Nat. Mus., 1881, p. 401. 



