100 CRETACEOUS PELECYPODA 



and should Goldfuss' figure, as I explain it, not prove correct, we must probably search after 

 the relations of this species in the genus Legumen, which I have previously noticed (p. 96). 



IQ.—Solen PelscJwM, Keys., (Eichwald, Leth. Ross, xi livr., 18G7, p. 787,) has the general 

 form of a Pharella, and occurs in beds which are supposed to be of Neocomicn age. 



Mr. Eichwald also supposes that the beds on the Aral Sea, from which Abich quotes a 

 species under the name of Soke. Lamarckii {=^Solec. Beshayesii, Des-Moul.), belong to the 

 cretaceous period. 



Zittel (Denksh. Akad., Wien, vol. xxiv, pt. 2, p. 110,) mentions from the Gosau deposits an 

 undetermined species of a Solecurtus. 



17. — Siliqua Moreana, d'Orb., only known by half the length of both valves; appears to be 

 remarkably straight in form. 



18. — Sil. Nereis, d'Orb., merely known by a very short note. 



19. — Sil. Iruncaiula, Rss., from the Senonian beds of Bohemia. 



20.—Sil. Petersi, Rss., (Denksh. Akad., Wien, 186.5, vol. xxiv, pt. ii, p. 109, pi. i, fig. 3,) is 

 from the beds of the Alpine Gosau formation. 



•■Zl.—Solenaria affinis, Eichw. sp., (seep. 95). Eichwald (1. cit.) says that this species is 

 probably allied to " Legumin. Schuhmacheri, Reuss," the name of which is unknown to me. The 

 same author (loc. eit., p. 289), notices a fragment of a somewhat allied, but much smaller species. 



22-27. — The following species are recorded by Meek in his Check list of North Am. creta- 

 ceous fossils (Smiths. Mis. Coll., No. 177, p. 15) : SUifiua hiplicata, Conr., and S. crefacea, Gabb; 

 Pharella dakotensis , Meek and Hayd. ; Legumen appressa, Con., Leg. eliipiica, Com:, and Leg. 

 j}la!ia/ii, Gahh. For the first of these species Conrad proposed the generic name Leptosolen, as 

 already mentioned (see p. 96). 



28. — Romer describes from Texas Sol. irradians, which may with equal probability be a 

 Gari (Psammobiaj , or a Trapezium. 



29. — Siliq. ausfralis, Gabb, at first described under the name of CiMellus, has the general form 

 of this genus, but is a higher shell. The species is from Chili. 



30-3a. — Gabb describes in the Palseontology of California, vol. i, p. 146, &c., Solen parallelus, 

 Pharella alta and Siliqua oregonensis ; the last species has quite the form of a Solemya, regarding 

 the position of the internal umbonal rib. 



3,3.34. — Another species, S. Biegonenms, is referred by the same author to the sub-genus Solena 

 (ibid. p. 213, pi. xxxii, fig. 280). More recently (ibid. vol. ii, p. 176,) Gabb adopts for the 

 species the sub-generic name Ili/pogella, pronouncing this apparently to be identical with Conrad's 

 Plectosolen. The same author also describes another species S. (Hypog.) cnncalus from California. 



35-38. — Four species occur in the South Indian cretaceous deposits, Siliqua limata, Pharella 

 delicatula, Solecurli/s obscurus, and Tagelus Alherlinns. 



The Tellina angulafa and Pandora eequivalvis of Deshayes both probably come near 

 Pharella ; the former is, as regards external shape, not to be distinguished from some species of Azor. 



Thus out of a number of 37 species recorded under the family SOLENID^ there are about 32 

 which, at least to a certain extent, admit of an approximate generic determination. Of these there 

 are only two species which possibly belong to the SOLENIN.E, namely, the somewhat doubtful Solen 

 parallelus, Gabb, from America and the remarkable Soleiiaria affinis, Eichw., from Russia. All 

 the other species, and some more which on account of insufficient preservation have not yet received 

 specific names, belong to the puarellin.k. Out of these again most of the species externally 

 ai)pear to resemble forms like Azor, Pharella, Tagelus, and others are fairly distinguishable as Siliqua. 

 Howevei', until the hinges, the pallial and the muscular impressions of the various species are 

 known, it would be in vain to expect a final settlement of the numerous objections which at present 

 can be made against the generic classification of the cretaceous forms. 



