The Systematic Position of Stylophorus caudatus. 447 



LIII. — The Systematic Position of Stylophorus caudatus. 

 " By C. Tate Regan, M.A. 



In a recent paper (P. Z. S. 1907, p. 634) I proposed the 

 name Allotriognathi for a new suborder of Teleostean Fishes 

 to include the Selenichthyes (Lamprididae), Histichthyes 

 (Veliferidse), and Tseniosomi (Trachypteridae and Lophotidae). 

 Of the Stylophoridae I could only say (p. 643) : " The remark- 

 able Stylophorus has usually been placed with or near the 

 Trachypteridae ; the single known specimen is not in good 

 enough condition for me to offer any suggestion as to its 

 relationships/' 



By a remarkable coincidence Dr. E. 0. Starks, of 

 Stanford University, was at that time engaged in describing 

 the anatomy of a second example of Stylophorus caudatus, 

 captured to the south of the Galapagos Islands at a depth 

 of 300 fathoms *. The results of his researches have 

 just come to hand in the form of an illustrated memoir 

 entitled "The Characters of Atelaxia, a new Suborder of 

 Fishes" (Bull. Mus. Comp. Zool. lii. 1908, p. 17). This 

 leaves no doubt that Stylophorus is a highly specialized 

 Tamiosome, and the definition of the Allotriognathi may be 

 modified in order to include this aberrant form, the Atelaxia 

 ranking with the Selenichthyes, Histichthyes, and Tamiosomi, 

 as a fourth division of the suborder. 



The diagnosis of the Allotriognathi, emended in order to 

 include Stylophorus, is as follows : — 



" Supra-occipital well-developed, separating the parietals ; 

 no opisthotic. Maxillaries typically free, protractile, each 

 with an outer blade and an inner posterior process ; no 

 supramaxillaries ; lower jaw composed of dentary, articulare 

 and angulare. Palatine, if present, without maxillary 

 process. Vertebral column of solid centra which are co-ossified 

 with the arches. Gills pectinate: Pectoral arch attached to 

 t lie cranium ; no mesocoracoid ; post-clavicle elongate, of a 

 single piece. Air-bladder without duct. Fins without true 

 spines (except sometimes the first one or two rays of the 

 dorsal) ; pectoral fin with horizontal or subhorizontal base ; 

 pelvic fins, if present, below or a little behind the pectorals, 

 tormed of from one to seventeen articulated rays ; pelvis, if 

 present, comprising a pair of erect subtriangular bony plates, 



* 1 he type in the British Museum was taken between Cuba and 

 Martinique more than 100 years ago. 



