374 Zoological Society : — 



HyPOCNEMIS SCHISTACEA. 



(S . Ccerulescetiti-schistacea unicolor : tectricum alarium omnium 



apicibus minute alba punctatis : rostro et pedibus nigris. 

 Long, tota 5'0, alse 2 "5, caudse 20. 

 Hab. Upper Amazon ; Rio Javarri {Bates). 

 Mus. Brit. 



In the general form and somewhat slender bill this species resem- 

 bles H. erythrophrys ; but its uniform colouring renders it easily dis- 

 tinguishable from that and other described members of the genus. 



Additional Observations on the Genus Furcella. 

 By Dr. J. E. Gray, F.R.S., etc. 



Sir Everard Home, as I stated in my former paper*, figured the 

 fragment of the vaulted continuation of the tube that closes its lower 

 ends, for the shelly valves of the animal. Considering this as an 

 accidental mistake, I took no further notice of it. An eminent com- 

 parative anatomist having observed, — " In the great Teredo arenaria, 

 which lives in soft mud, the valves are wanting, according to Dr. 

 Gray, or their homologues form the convex cap closing the periodi- 

 cal growths of the calcareous tubes " ("Mollusca," in Ency. Britan. 

 353), I feel it incumbent on me to show the reasons why I cannot 

 consider the " convex caps " closing the calcareous tube to be the 

 homologues of the true valves, which, in my paper, I have said are 

 entirely absent. 



First. The caps have the structure, and are continuations of the 

 tube, and have no relation to the usual valves of the Teredo in their 

 form or structure. 



Secondly. The convex caps here referred to are evidently identical in 

 structure and formation with the convex cap that is found on the end 

 of the tubes of the allied genera ClavageUa and Aspergillitm ; and 

 as these genera have the shelly valves of the animal in their proper 

 situations, on the sides of the body, quite distinct from the convex 

 caps, I think it is conclusive that they are not the homologues of the 

 valves, in those genera, as both the valves and the caps which are 

 considered as their homologues are present together, so that I must 

 consider the convex cap in those genera as I do in Furcella, only as 

 a continuation of the shelly tube in which the animal lives, and 

 having no more affinity with the shelly valves than the tube of Gas- 

 trochcBna and some Lithodomi and other perforating Mollusca. 



Thirdly. It is to be remembered that some species of the true 

 genus Teredo, which have distinct shelly valves, also form a shelly 

 convex cap at the base of their tube in front of the animal, exactly 

 similar in structure and situation to the cap of the genus Furcella, 

 as I mentioned in my former paper ; so that I cannot consider it only 

 as a septum formed by the animal for its protection during the period 

 of rest in those species of Teredinidce which have true, well-deve- 



* See Annals, vol. i. ser. 4. p. 2f>5. 



