410 Mr. H. J. Carter on Dracunculus. 



which ai'e principally required in the direction of the axis of the 



shell The animal differs from Solen in having its siphons 



free, instead of occupying a common tube ; and in having an 

 expanded instead of a conical termination to the foot." 



I may also add the following from the characters of the shell : 

 " Epidermis easily detached when dry, folding over the edges 

 and extremities of the shell, and connecting the hinge-margins." 



In Novaculina there is a strong prominent external ligament, 

 and its internal prolongation is received into a cavity communi- 

 cating by a lateral posterior opening with the interior of the 

 shell ; the salient re-entering teeth — three in the left valve, and 

 two longer in the right — lie under the beaks anteriorly to and 

 quite independent of the ligamental cavity; whereas in Tany- 

 siphon two of the teeth in each valve form, as it were, a portion 

 of the wall which separates the ligamental cavity from the in- 

 terior of the shell, and the anterior tooth in the right valve 

 alone inclines to an independent direction. 



For comparison with Dr. Cantor's drawing of the animal of 

 Tanysiphon, I add a sketch which I made from a living example 

 of Novaculina in Calcutta. It will be observed that the animal 

 failed to protrude the foot, so as to exhibit its form to the extent 

 reached in the Jumna specimens, and that the siphons were also 

 less extended. 



Cheltenham, 29th April, 1858. 



EXPLANATION OF PLATE XIL B. 



Fig. 1. Tanysiphon rivalis, natural size (nearly). 

 Fig. 2. Siphonal tube and siphon, magnified. 

 Fig. 3. Left valve of Tanysiphon rivalis. 

 Fig. 4. Novaculina Gangetica, with animal. 



Note. — Dr. Cantor's figure having reference chiefly to the animal of 

 Tanysiphon, the part which represents the shell fails to exhibit the general 

 form correctly, especially in the umbonal region. The beaks are too pro- 

 minent, and are deficient in the breadth which characterizes the genus in 

 this as in the corresponding part of Novaculina. Fig. '^ shows the true shape. 



XXXIX. — Observations on Dracunculus in the Island of Bombay . 

 By H. J. Carter, Esq., H.C.S. Bombay*. 



Since my " Note on Dracunculus in the Island of Bombay" was 

 communicated to the Society in October 1853, and published 

 in the new series of their ' Transactions ' (No. 2. p. 45), I have 

 continued to give my attention to the subject when opportunity 

 offered, and have thus been able to correct, to add to, and to 



* Communicated by the author ; having been read before the Medical 

 and Physical Society of Bombay, Feb. 6, 1858. 



