A Revision of the Genus CoryJoras. 209 



Fiff. 5. Spines on terminal joints of leg. 



Fig. 6. Dorsal view ; walking-legs removed. 



Fiff. 7. Terminal joints of ovigerous leg. 



Fiff. 8. Spine of oviger. 



Fiff. 9. Palp. 



FiQ. 10. Chela. 



Fiff. 11, Oviger with egg-mass. 



XXIV. — A Revision of the South-American, Siluroid Fishes 

 (f the Genus Corydoras, with a List of the Specimens in the 

 British Museum [Natural Ilistort/). By C. Tatp: ReGAN, 

 M.A. 



(Published by permission of the Trustees of the British Museum.) 



The Callichthyid fishes with the occipital process extend inp: 

 to the plate at the base o£ the dorsal fin-spine may be divided 

 into two genera — Corydoras, Lficep., 1803, with 6 to y soft 

 rays in the dorsal and the base of the fin about eqttal to its 

 distance from the adii)ose fin^ and Brochis, Cope, 1871, with 

 9 to 11 soft rays in the dorsal fin, which is more extended, its 

 base considerably n;ore than its distance fiom the adipose 

 fin. In his recent list of Neotropical fishes Eigenmann 

 recognizes the genus Osteogaster, (^ope, including therein two 

 species which have the humeral shields somewhat larger than 

 usual. One of these is a Corydoras, viz. C. eques, Steind., 

 which is closely related to C. nattereri and still more closely 

 to C. macrosteus, described below as new; the other is of a 

 very diflierent type, and should, in my opinion, be placed in 

 the genus JBrochis ; it is Z>, sjilendens^ Casteln. 



There are so many species of Corydoras unrepresented in 

 the British ]\]useum collection and of uncertain position that 

 I find it difficult to make a satisfactory key to the species. 



Synopsis of the Species. 



I. Interorbital width \ the length of head or less ; snout more than | 



the length of head. 



Scutes in upper lateral series 23 1. treiilii. 



Scutes iu upper lateral series 26 or 27 2, kronei. 



II. Interorbital width | the length of head or more. 



A. A series of spots along the side and a second series on the back. 



1. Diameter of eye 6 or 7 in length of head. . 3. micr acanthus. 



2. Diameter of eye 4 or 5 in length of head. 



Head 3f in the length 4. microcejjhalus. 



Head 3^ to 3| in the length 5. paleatzis. 



3. Diameter of eye 3^ in length of head .... G, ffarlei. 



