lU CRETACEOUS PELECYPODA 



are vertically erect, laterally compressed, and generally bifid, with tlie exception 

 of the most anterior tooth in the left, or sometimes in both valves : this peculiarity 

 is indeed so characteristic as compared with the hinge of Vemis that no doubt can 

 he entertained in the determination of the shell ; it is the most constant of all 

 the other characters of the sub-family, and when combined with a compressed 

 shape of the shell, as, for instance, in F. Uterata, Linn., the resemblance of such 

 forms to Venerupis (of the Fetricolid2e,J is, as already mentioned, striking. 

 The only rather solid shells are those belonging to the type of T. imiguis, Chem., 

 mostly approaching in character some species of Meretrix. 



In 18G4 Dr. Ed. Romer published in the Malaco-zoologische Blsetter "a 

 critical synopsis of all the species belonging to Tcqyes, a sub-genus of the genus 

 Venus." The author admits fom* sections of Tapes, each under a different name. 

 They are TaratapesC^Textrix, Eom.,) Farembola, Ainyydala, and Hemitapies. 

 I have already recorded my opinion with regard to the propriety of the names 

 which Dr. Homer gives to his sections or sub-sections. I have also stated 

 that it would not be advisable to interfere with Dr. Romer's work as long as it is 

 in progress. So far, therefore, as the recent forms are concerned, I shall restrict 

 my remarks to a few suggestions, illustrating my ideas on the classification of the 

 TAPESIN.E by quotations of well known species as types. 



1. Faratapes, StoL, 1870, (Textrix apud Roraer, not ifZem Blackwall or 

 Sundewal, 1833, ArachnoideaJ. Type P. textrix, (Chem.). Shell much elon- 

 gated, compressed, outer surface smooth. 



2. Semitapes apud Romer; type Tapes pthiguis, (Chem.). Shell inflated, 

 solid, ventricose, especially at the umbones, which are incurv^ed, more or less 

 narrower posteriorly ; outer surface smooth. 



2a. Homer refers to the above as a special section Venus rimularis of 

 Lamarck, which has a rhomboidal shape and concentric sulcations. This is a 

 somewhat different type of shell, and could be considered, moreover, as a section of 

 PuUastra, or perhaps still better as distinct from both and classed with T. denti- 

 cidata, Sow., the Californian Tap. straminea, &c., the shells of these species being 

 solid, with the inner margin crenulated. 



3. Fullastra, Sow., 1827, (as emended by H. and A. Adams). Shell 

 elongated, moderately inflated, anterior side peculiarly narrowly roimded ; 

 surface of valves concentrically sulcated or striated ; pallial sinus ascending, rather 

 higher than in other forms of Tapesina;. The type of this is Ven. malabarica, 

 Chem., or Taj), turgklula, Desh. The species are rather numerous ia our eastern 

 seas; Venus cor of Sowerby from Cutcli also belongs to it. 



3ff. A number of species which are strongly inflated, cuneiform, thick and 

 short in front, and gradually becoming narrow towards the posterior end, thus 

 in this respect very much resembling Hemitapes, appear to form a special section. 

 Chemnitz's Venns striata is the most characteristic species of this group. 



4. Tapes, Megerle, 1811, f Paremboia apud Romer). Shell sub-rhomboidal, 

 compressed, beaks very small, surface of shell concentrically ridged or sulcated, 



