312 CRETACEOUS PELECYPODA 



U. BemoncUa, Gabb, 18G9, (Pal. Calif., II, p. 270). Shell compressed, 

 clongately sub-quadrate, inequilateral, the beaks being sub-anterior; ligament 

 very short, external; hinge composed of three moderately diverging, elongated 

 cardinal teeth and one long posterior lateral in the left valve ; those of the right 

 would appear to be similar and corresponding to those of the left. " The middle 

 cardinal of the left valve is transversally striated, as in Trigonia, and is slightly 

 o-rooved on its face ; the anterior is linear and smooth, and the posterior is also 

 smooth, at least on its posterior face. The posterior lateral and its corresponding 

 cavity are irregularly rugose. In the right valve the anterior tooth is as large as the 

 middle, the posterior is linear;" type, B.furcata, G., from cretaceous beds of Mexico. 

 The only other species which I believe to belong to this genus is the 

 peculiar Astarte Bronnii, described by Prof. Krauss from the upper series of some 

 fossiliferous beds near the Algoa Bay (South Africa), which beds he at the time 

 (1839) considered to be equivalent to the " Lower Greensand." Very likely Krauss 

 was correct in his first identification, though others have subsequently pronounced 

 the same beds to be of Jurassic age. Krauss (Nov. Act. Acad. Coes. Leop., xiv, 

 pt. ii, 1850, p. 449, pi. xlviii, fig. 1), already mentioned that A. Bronnii probably 

 belongs to a new genus. Its hinge closely corresponds with that of BemoncUa. 

 Each valve has three elongated cardinal teetli, the median ones being the strongest, 

 and there also appears to be one very long, sub-marginal tooth in each valve 

 present. The median tooth of the right valve is transversally striated on both 

 sides, in the left only on the anterior side, and here the first tooth is also striated 

 on the posterior side, opposite the former. The shell is also of a form similar to 

 the type species of BemoncUa, elongated, with the beaks almost anterior, but some- 

 what more tumid and posteriorly more attenuated. The valves seem to have been 

 in the present species gaping posteriorly, on which point Gabb was too uncertain to 

 give a decided opinion. 



It is not improbable that some other fossil species of Astarte and Cmssatclla 

 will be shown to belong to the present genus, as, for instance, Cr. Banded, Coq., 

 Pal. Prov. Const., pi. siii, fig. 5. 



7. Ileekia, Gabb, 1864, (Pal. Calif., I, p. 181). Shell oblong, sub-ineqixilateral, 

 posteriorly rounded, anteriorly somewhat produced and turned upwards hook- 

 like, terminating in a point ; surface marked with strise of growth only ; hinge 

 with "two robust, triangular teeth on the right valve, and one large and one 

 small one on the opposite side, the large one being received between the two 

 of the right valve; posteriorly on each side is an indistinct lateral tooth." 

 " A short robust plate separates the anterior muscular scar from the cavity of the 

 beak." Type, M. seUa, G., and two others are the only known species of the 

 genus ; they are fi"om cretaceous deposits. 



It is, as Gabb remarks, uncertain where to class this peculiar genus, but 

 the general character of the shell and of the hinge-teeth appears to me to have 

 .a greater similarity to the hinge of Schizoclus and Neoschizodus, than to that of 

 any other known genus. 



