572 Mr. C. T. Regan on the 



pelvics 6-rayed. Barbels three pairs, raaxillary and two 

 mandibular ; anterior and posterior nostrils -wide apart. 

 Jaws toothed; palate with or without teeth. Palatine rod- 

 like, articulating with the side of the lateral ethmoid ; 

 pterygoid, when present, slender, having the appearance of 

 an ossified ligament connecting palatine and mesopterygoid ; 

 latter small, lying between the well-developed metapterygoid 

 and the lateral ethmoid. Post-temporal present ; supra- 

 cleithrum firmly attached to skull, with a well -developed 

 lower limb; mesocoracoid present; hypocoiacoids meeting 

 and interlocking behind the symphysis of the cleithra. 

 YertebriE 42 to 60 (15-20 + 25-43) ; riljs on parapophyses ; 

 parapophysis of fourth vertebra a horizontal lamina witli a 

 more or less distinct stout anterior ramus which is rigidly 

 united with the stem of the supra-cleithrum ; air-bladder 

 typically large and free. 



Neotropical, fresh Mater fishes. 



This family is closely related to the Indian and African 

 family Bagridse ; it includes a number of diverse types, but 

 is undoubtedly a natural group. 



The absence of a nasal barbel usually distinguishes the 

 Pimelodida^ from the Bagrida, and the tew Bagridre which 

 have no nasal barbel differ from the Pimelodidje in their 

 united gill-membranes. The skeleton of the two famiHes is 

 extremely similar, but the lateral ethmoid facet for articu- 

 lation of the palatine is hardly ever strictly lateral in the 

 Bagi'idee, and the pterygoid, when present in tiie Pimelo- 

 didffi, is unlike that of either the Chrysichthyinae or the 

 Bagrinse. Since the two groups are large, varied, and 

 geographically distinct, and seem to form the starting-point 

 for the evolution of most of the Siluroids of South America 

 and of Asia and Africa respectively, it seems best to recognize 

 them as distinct families. 



The following arrangement includes many of the principal 

 genera, but some I have not seen and am unable to place : — 



I. Ptorvproid present, slender, attached anteriorly to lower surface of 



palatine and posteriorly to outer end of the transverse, creseentic 

 ineso])terygoid ; parajiophyses of fourth, fifth, and sixth vertebne 

 laminar, united bj' euture ; air-bladder normal. 



CaUophysus, Pimelodus, Plra- 

 iniita7i(i, Sciades. 



II. Pterygroid absent ; mesopterygoid laminar, attached in front to 



lower face of lateral ethmoid and behind to anterior edge of 

 metapterygoid ; air-bladder normal. 

 A. Anterior and posterior rami of parapophysis of fourth vertebra 

 connected at the base only ; si.\tli vertebra free, with normal 



transverse process riincIodtUa, lihamdia, Hepta- 



pfenis, yunntK/ldiiis. 



