APPENDIX. No. IV. 419 



Velella. To this genus likewise some additional characters may be added. 

 The disc is oval and cartUaginous, having an oblique crest on its upper 

 side. The disc itself is composed of t\ro tliin oval plates joined together by 

 sevei'al concentric septa. The whole of tlie cartilaginous part is covered by 

 a dense membrane, and its inferior surface is covered by ten taenia, which 

 surround its stomach ; those towards the centre are terminated by suckers, 

 those towards tlie margin are longest, and appear to be simple. The 

 stomach is oblong, and the mouth very prominent. The membrane in 

 passing from the upper part of the disc, to the lower, is produced beyond its 

 margin, and the produced pai-t is consequently composed of two membranes, 

 which are united towards the marjrin of the disc* 



1. Veleila scaphidea. Crest set on the disc from left to right ; its apex abruptly 

 produced. 



Veleila scaphidea Peron et Le Seuer. Atlas, pi. xxx. 



2. Yeldla pyramiial'is. Crest set on the disc from right to left; its apex 

 gradually produced, pyramidal. 



Taken in plenty in 26, 34, N. lat. IS, 28, W. long. 



From the MS. observations made by Mr. Cranch, it is evident that a box 

 containing specimens of marine animals, preserved in spirits, and a very large 

 portion of the birds, have been lost. I have before remarked, that of the 

 birds received, those enumerated, were the only specimens in a state fit for 

 examination ; the greater part being totally desU-oyed by insects. 



* This produced membrane is to be observed in all the species, and therefore cannot 

 be taken as a specific character, as has been done by Lamarck, for our European species. 



