122 CRETACEOUS PELECYPODA 



All Tellwibm are inhabitants of sandy shores ; they all bury in mud and 

 the greater number are purely marine species. Of the garin^ which are more 

 numerous in Australian seas than anywhere else, there are about 120 species 

 known ; of tellininm which are in all tropical seas numerous, but largest and finest 

 in the eastern seas^ there have been as yet about 360 species described. 



Cretaceous species of Tellintd^e, 



Pictet and Campiche in their review of the cretaceous species of this family refer them to 

 the genera Tellina, Arcopagia, 'Psammohia^ Sanguinolaria, and Mactrom^a, (see Pal. Suisse 4^^ 

 ser., 3^e part., pp. 133, &c.). 



1. — Mactfomya Couloni is the type of the genus; no other species is as yet known, and it is no 

 doubt necessary to be very careful in transferring an imperfect fossil shell from one o-enus into 

 another, for the confusion is in such cases often endless, and no benefit results either to the con- 

 chologist or the geologist. 



2. — Of Sanguinolaria also only one species has been described, S. cretacensis, Conrad, from 

 Alabama ; it has quite the form of recent species of that genus, but the hinge-teeth have not been 

 observed on the fossil. I cannot see for what reason the shell has been referred to Cyprimeria by 

 the same author (Am. Jour. Conch., iii, p. 9). 



G-ari and allied genera, I have already mentioned that there is great difficulty in determinino- 

 which of the species usually quoted as Gari (=^ PsammoUa) really belong to that genus and which 

 to others. Judging from the preparation of the hinge-teeth of the two species which occur in the 

 Austrian Gosau formation, and of three species from the South Indian cretaceous rocks, I came to 

 the conclusion that these species do not even belong to the sub-family garina^, but must be classed 

 in a separate genus in the tapesin^, (family Veneridae). However, from want of sufficient 

 data regarding the hinge-teeth of other species, I shall be obliged to retain here those species which 

 are closely allied in form to Gari and others, though this statement must be accepted with the 

 distinct understanding that there is as yet not a single case known in which one of those species 

 has been satisfactorily ascertained as belonging to any of the genera of the Garin^. 



3-5. — Gari Giiilleroni, tenuis and Valangiensis, have the general form of P^(27^?^y?6?^^^, but are 

 rather less high. 



6-8. — Gari EscJieri, intermedia and Studeri, have the posterior end radiately ribbed; there is a 

 large number of such recent forms of Gari, they are chiefly of small size. 



Gari compresm, d'Orb., sp., Solen elegans, Math., [non d'Orb. or Desh.], impar, Zittel 

 [ = elegans, d'Orb.),-^ discrepans, Duj., Arnaiidi, Coq., (apparently closely aUied to the last), and 

 Sitessi, Zitt., &c., are all species of tafesinal, as I shall state in more detail subsequently. 



Gueranger^s (Album paleont., 1867, pi. xv,) three species, Capsa Cenomanensis , CoIotkb ^nd 

 concentrica, are closely allied to d^Orbigny's elegans = ZittePs Fs, impar, and no doubt also 

 belong to the same type of tapesinae. 



Gari texta, Gabb, (Pal. Calif., I, p. 155,) has the general form of the genus, but the pos- 

 terior plicature is apparently indistinct, as in Hiatiila. 



I may here mention the peculiar shell described by N ill son as Venus? ejcuta ; it may prove 

 to be a species of the garinae (Petr. Suec, p. 17). 



* Matheron's name elegans must stand for tjie jT^i^e^-form ; Deshayes' species elegans is a Gari; 

 d'Orbigny's name elegans was changed into impar by Zittel, who (Denksch. Akad., Wien, vol. xxiv, p. 120,) iden- 

 tifies the Gosau with the French species, although, judging from the figures, there are considerable differences between 

 the two ; the author does not say whether he had compared authentic specimens of the latter with the former. 



