212 



IrjHTHYODECTES MULTIDENTATUS, Cope. 



This species was first described from a premaxillary and part of a max- 

 illary bone, from the Smoky Hill River ; a second and more perfectly- pre- 

 served skeleton, obtained by Prof. Merrill from the headwaters of the 

 Solomon River, adds much to our knowledge of it. The first-mentioned 

 specimen was described as follows: 



'.' In this fish, we have the convex premaxillary of the larger species, with 

 more numerous (twelve) teeth than in any other of the genus. Those of 

 largest size are the first three, the last being small. The second and third 

 are about equally prominent, and more so than the first. The bone is much 

 contracted above ; there beiug an excavation on the anterior border, and con- 

 traction from behind. The superior edge is thin, and without trace of artic- 

 ular surface. Alveolar edge somewhat rugose. The maxillary is both 

 narrow and thin, but is only partially preserved. It bears five teeth on 

 m .01. One of these, with complete crown, displays a longitudinal angle on 

 the antero-interior. face. Length of the premaxillary, m .039; depth of the 

 premaxillary (oblique), CT.023 ; length of its tooth-line, (T.025." 



The second specimen is represented by a cranium with maxillary bone 

 and scapular arch, vertebras and ventral spines, etc. The specific characters 

 are well exhibited in the dentition. There are thirty teeth and eighteen 

 empty alveoli in the maxillary bone ; and the anterior apex of the same, 

 which is broken off, probably supported four additional ones.. The crowns 

 have a subround section, and differ from those of other species in being 

 marked with shallow sulci and longitudinal angles and ridges. The most 

 prominent ridsjes are, one on the middle of the external face, and one on the 

 outer side of the anterior face, but there may be two or three on the outer 

 line and on a few posterior teeth ; the outer face is smooth. The fragment 

 with tooth, above described as typical, belongs to the distal part of the jaw. 

 There are shallow grooves at the bases of the crowns of most of the teeth. 



The cranium has an elevated crest, which stands on the narrow median 

 bone which I suppose to be supraoccipital. On each side, and just behind 

 the crest, the parietal bone rises as a posteriorly-directed process. The 

 epiotic also forms a strong latero-posterior angle. The pterotic extends roof- 

 like on each side : its anterior part abruptly depressed below the posterioi\ 

 The postfrontal forms a short transverse process, which is preceded by a con- 

 cave excavation of its free border. The vertical position of the malleolar 

 process of the prefrontal shows that this species possessed the subvertical 

 mouth already ascribed to the Portheus wo/oasus. 



The scapula is much like that of Portheus, and in the specimen stands 

 ou a level with the orbit. The ventral spine is of relatively large propor- 

 tions, and its superficial dense layer is marked with rows of delicate, im- 

 pressed punctse, which are sometimes confluent into grooves. The first 

 cervical vertebra is unmodified and grooveless ; the dorsal vertebrae are 

 grooved. Length of cranium, 0"'.1.j4; diameter of (irst vertebra, m .02U ; 

 depth of maxillary at middle, U"\023 ; width of ventral spine, (T.020 ; length 

 of articular face of scapula. 0"'.031 ; width of clavicle below scapula, m .040. 



