172 PKOCEEDINGS OF THE MALACOLOGICAL SOCIETY. 



tooth, which fills the space in the other valve, so that the differences 

 are considerable. No species of Baroda has yet been found in 

 England. 



Venerella. — This name was proposed by Cossmann in 1886 (op. cit.) 

 for a small group of Eocene shells which had been wrongly referred 

 to Venerupis by Deshayes. He enumerated five species, the first 

 being V. Mermonvillensis, Desh., which has been accepted as the type. 



After indicating the points in which these shells differ from 

 Venerupis he says : " They have, in fact, the greatest affinity to Venus, 

 so that I propose to make them merely a group of this genus under 

 the name of Venerella.^' It is evident that by Venus he meant 

 a comprehensive genus such as that adopted by Fischer in his 

 " Manuel de Conchyliologie " (1887), a genus with many subgenera, 

 all of which are now regarded as separate genera. It is to be noted, 

 however, that Fischer did not place Venerella under Venus, but under 

 Tapes, in which he also included Baroda. Dr. Dall, in his Synopsis 

 of the Veneridse (1902), places it near the group which he calls 

 Venus (i.e. Mercenaria), and as a section of Katelysia (Roemer), but 

 the affinity of Venerella with these groups seems to me very remote. 



The following description of Venerella is compiled from the 

 particulars given by M. Cossmann, and from a study of specimens 

 of two species for which I am indebted to him : — 



The shell is small and ovate, concentrically striated, Avith a super- 

 ficial circumscribed lunule. The hinge has three cardinals in each 

 valve ; in the right the anterior and median are short and directed 

 forward ; the posterior is simple (not bifid), and nearly parallel 

 to the nymph, so that it makes nearly a right angle with the other 

 teeth, while the intervening part of the hinge -plate is deeply 

 excavated. In the left valve both the median and posterior teeth 

 slope backward, while the hinge-plate is excavated in front of the 

 median, and is truncated beneath the posterior tooth. The pallial 

 sinus is deep, ascending, and rounded. The valve-margins are smooth. 



The resemblance of the hinge, above described, to that of Baroda 

 will easily be perceived ; and while M. Cossmann was amply justified 

 in separating the group from all other Eocene forms of Venus, I think 

 that Fischer had good reason for placing it near to Tapes and Baroda. 



Venerella may also date its existence from Cretaceous time, for the 

 Tapes nuciformis of Holzapfel,^ from the Chalk of Aix-la-chapelle, 

 seems to be referable to it, having similar teeth and being nearly 

 orbicular in shape. 



Besides the five Eocene species which were included in this group 

 by M. Cossmann, it appears to me that four of the species which he 

 placed under Mercimonia must really belong to Venerella, if their 

 hinges are correctly represented in the figures of Deshayes. As 

 a matter of fact M. Cossmann did not give any definition of Merci- 

 monia, nor did he indicate how it differed as a group from Venerella. 



Die Mollusken der Aachener Kreide " : Palseoutographica, vol. xxxv (1SS9), 

 p. 165, 



