114 KANSAS UNIVERSITY QUARTERLY. 



Length of fish, as preserved 240 mm 



Estimated length 250 " 



Length of vertebral column 175 " 



Greatest width, just back of ppctoral liii 27 " 



Length of caudal fin. upper loh'' 22 " 



Length of pectoral fin % 7 " 



Length of ventral fin g " 



The specimen lies on the shell of a large Inoceramus, explaining 

 its excellent preservation. Close by are the remains, as seen in the 

 illustration, of several examples of a small fish of unknown affini- 

 ties, hitherto undescribed. The horizon is the Niobrara Cretaceous 

 of the Smoky Hill River. The specimen was collected by Mr. H. 

 T. Martin in 1895. 



The family Hoplopleurids, in which this genus must for the 

 present be placed, includes apparently heterogeneous forms, and 

 concerning which there is a diversity of opinion. The definition of 

 the family, as given by Zittel, will not include the present genus, 

 and perhaps some others located in it b}' that author. He includes 

 the following genera: BdonoyJiyncliiis, Saiiriclithys, Sai/rorha>iiphus, 

 Eitryop/iili/s, ? PaliiiiplHinus, Paiitopliiliis, Eurygnatluis, Pliniliophorus, 

 Dcrcetis, Lcptotracheliis, ? Aspidopleurus and Pelargorhxiuhus, all 

 from the Cretaceous. Blocliiiis is placed b)^ him in a separate family, 

 the Blochiidae. 



BclonorJiyiichiis and Saiiricht/iys are located by Woodward in an- 

 other family, the Belonorhynchid?e, widely separated from the 

 Hoplopleuridae. Lydekker, in his Manual, includes in this family 

 the following genera: Dcrcetis {Lcpto/rac/ic/iis), Aspidopleurus 

 Bloc/iius. Plintiiophorus. Pclargorlixnchus and Sai/rorliainp/ii/s. Euryop- 

 hiliis he locates in the allied family Enchodontidae. 



"The family Hoplopleuridee was established by Pictet for fishes 

 which were devoid of scales properly so-called, but which are pro- 

 tected on the back and sides by rows of scutes. The head is long 

 and the jaws are provided with pointed teeth of unequal size. The 

 bones of the head are frequently sculptured or granulose. The 

 genera associated in this family by M. Pictet are: Dercctis Agassiz, 

 Sauror/ia/iipliiis Heckel; Lcptotraclicliis v. d. Marck; Plintlwpliorus 

 Giinther; Euryopliilus Pictet; Pciargor/iyuc/iits v. d. Marck. The 

 fished included in the genus Dcrcetis were considered by Agassiz to 

 resemble the sturgeons in the arrangement of the dermal scutes, 

 and were grouped amongst the Ganoids. Heckel held the same 

 opinion with respect to the position of Saurorhamphiis, and Von 

 der Marck also places the genera PelargoriiyncJuis and Lcptotrac/ic/us 



