NO. 1186. RELATIONSHIP OF DINOLESTES LEWINI—STAEES. 115 



in by members of the family Cheilodiptericlne. They are of uo great 

 importance. 



This, as has been said, is without considering the position of the 

 ventrals. As the Percoid fishes have thoracic ventrals, and the mem- 

 bers of the suborder Percesoces, under which the Sphyrtenidce is 

 placed, have abdominal ventrals, it is cUfiQcult to see how Binolestes 

 could have been thought to be related to Sphyrcvna unless the ventrals 

 were interpreted as being abnormally anterior abdominal ventrals. 

 The ventrals, however, prove to be typical thoracic ventrals with the 

 anterior point of the pelvic girdle interposed and attached between 

 the opposing clavicles near their lower end above their symphysis. 

 Anterior abdominal ventrals might have the point of the pelvic g-irdle 

 touching* the clavicles or even extending slightly under them, but 

 never interposed between them. 



Another character that refutes the Sphyraenoid relationship of I) ino- 

 lestes is the lack of the long processes developed backward from the 

 epiotics and supraoccipital crest, which are possessed in a greater or 

 less degree by all the Percesoces and reaches its greater development 

 in Sphyrcena. 



A more important difference is the structure of the teeth. Though 

 both Binolestes and Sphyrcena have large backward-directed canines, 

 they are entirely different in the way in which they are attached to 

 the bone of the jaw. The calcified tooth substance of the teeth of 

 Binolestes reaches only to the bone, where it is anchylosed or so incor- 

 porated with the bone as to make it difficult to distinguish the line of 

 junction. This attachment is effected by what Tomes calls "bone of 

 attachment." A substance resembling cement, but unlike true cement, 

 is developed from the periosteum rather than from the dental capsule. 

 Such teeth may be developed from sockets, but as the calcified tooth 

 substance is jjushed out the cavity behind fills with the bone of attach- 

 ment and becomes obliterated. The dentine never extends into a 

 cavity of the bone in the mature tooth. This is a Percoid character. 



The teeth of Sphyrcena, on the other hand, are set in sockets. The 

 attachment of teeth in alveoli is of such rare occurrence among fishes 

 and must be so deep seated that we can hardly interpret it as less than 

 a family character. Mr. W. G-. Eidewood, in a paper,' has this to say 

 in regard to this class of teeth : 



The tooth and bone are in organic continuity by means of a periosteal layer com- 

 mon to the tooth and the jaw; and this layer may remain nncalcified so that the 

 teeth can be pulled out of their sockets, as in some Caracinoid fishes; or "bone of 

 attachment" may, except in young teeth, anchylose the tooth to the wall of the 

 socket, e. g,, Sphyriena. 



But whether or not the tooth becomes cemented in, the enamel and 

 dentine extend into a cavity and do not become incorporated with the 

 bone. 



'Natural Science, YIII, June, 1896, p. 383. 



