62 ZOOLOGY OF THE VOYAGE OF THE BEAGLE. 



Mr. Darwin's collection contains two individuals of this species procured on 

 coral reefs at the Keeling Islands. As according to his notes made from the 

 recent fish, the posterior half of the body is bright orange, Bloch's figure may not 

 be so much overcoloured as is supposed by Cuvier and Valenciennes, who state 

 that he has represented of a bright red, what ought to be silvery grey and yellow 

 ochre. Perhaps the colours may depend in some measure on the season. Mr. 

 Darwin's specimens were obtained in the month of April. 



Genus— STEGASTES.* Jen. 



Corpus oblongo-ovale, compression. Caput obtusum. Os parvum, haud protractile. 

 Denies maxillares omnes incisores, parvi, cequales, contigui, uniseriati ; palatini 

 velutini, minuti. Ossa suborbitalia denticulata. Preoperculum margine adscen- 

 denti levissime denticulato. Operculum inerme. Membrana branchialis quatuor- 

 radiata. Pinnce verticales squamis covfertis fere omnino obtectce : dorsalis unica, 

 subcsqualis, membrana ad apices spinarum parum laciniata : ventrales radio primo 

 molli elongato. Lima lateralis sub terminationem dorsalis interrupts, Squamce 

 rostri et verticis parvce ; operculi et corporis magna, oblique dispositce ; omnes 

 levissime ciliatce. 



This apparently new form will enter into none of the genera established by 

 Cuvier and Valenciennes. The palatine teeth serve to detach it from the Scicenidce, 

 while this character, taken in connexion with the compressed body, and the 

 extreme scaliness of the vertical fins, require that it should be arranged with the 

 Chcetodontidce, or at least have a place in that large group to which Cuvier has 

 given the name of Squammipennes. It belongs to the second tribe in that family 

 characterized by cutting teeth ; and it would seem most nearly allied to Pime- 

 lepterus, but it does not approach that genus very closely, and may at once be 

 distinguished from it, by the teeth being without spurs behind, and the dorsal and 

 anal fins being more scaly. From Dipterodon, the only other genus in that tribe, 

 it may be known by its undivided dorsal, independently of other marked dif- 

 ferences. 



But though this genus requires to be arranged with the Chcetodontidce on the 

 grounds above mentioned, in all its other characters it comes much nearer that 

 portion of the Scicenidce which have the lateral line terminating beneath the end 

 of the dorsal fin ; especially Pomacentrus, which it resembles in the general form 



* Srtyaurj/s, tector. 



