90 



Length of the longest finger 2 7 



of the fourth finger 1 10 



of the thumb 3 



of the tibia 74 



of the foot and claws 4\ 



Expanse of wings 10 2 



2. OxN a New Genus of Mytilid^e, and on some Distorted 

 Forms which occur among Bivalve Shells. By Dr. J. 

 E. Gray, F.R.S., V.P.Z.S., President of the Entomo- 

 logical Society. 



(Mollusca, PI. XLI.) 



We have for several years had some specimens of large Myti- 

 UdcB in the Museum Collection which I have always regarded as the 

 types of a distinct genus, but have deferred from time to time their 

 publication, as I was informed that Dr. Dunker and others were en- 

 gaged on a monograph of the family. Dr. Dunker having published 

 the species without forming it into a group, I have therefore brought 

 it before the Society, and at the same time make some observations 

 on a peculiarity which the species presents. 



Stavelia, n. g. 



Shell inequivalve, inequilateral, subtrigonal ; umbo anterior ; the 

 front of the ventral edge sinuous, the flatter valve with a broad ex- 

 panded lobe on the front of the ventral margin, the more convex one 

 with a deep sinuosity to fit the lobe of the other valve. Anterior 

 adductor scar distinct, oblong ; posterior roundish ; submarginal 

 scar parallel to the edge of the shell, entire. Hinge toothless. Li- 

 gament and cartilage linear, marginal, rather short. 



Periostraca laminate, with elongated flat linear or tapering pro- 

 cesses. 



This genus differs from Mytilus in the inequality of the valve and 

 the sinuosity of the lower edge, in the entire absence of any small 

 teeth under the umbo, and in the paleaceous periostraca. 



1. Stavelia to rta. (PI. XLI. fig. 1.) 



Mytilus tortus et M. horridus, Dunker, Proc. Zool. Soc. 1856 ; 

 Reeve, Conch. Icon. t. 3. f. 6 & 9. 



Hub. North Australia and Philippines. 



I cannot discover any permanent character between the two spe- 

 cimens described by Dr. Dunker. 



The specimens of this genus in the Museum, and others which 

 have come under my observation, offer a peculiarity which I have 

 hitherto only observed in a very few other bivalve shells, and in none 

 to the extent which is presented in this species. 



