Freshwater Fishes from Costa Rica. 457 



Three specimens, 90 to 105 mm. in total length. 

 This species was hitherto known only from a single small 

 specimen (52 mm.) from Panama. 



Siluridae. 

 4. Arius evermanni, Gilb. & Starks. 



Depth of body 5 in the length, length of head 3? to 3§. 

 Breadth of head .1| in its length, diameter of eye 6-6^. 

 Fontanel produced into a groove which does not reach the 

 parieto-occipital ; parieto-occipital with a feeble keel ante- 

 riorly, which does not extend on to the occipital process, 

 which is broader than long, with straight or concave sides 

 and truncate or emarginate apex ; dorsal shield small, sub- 

 crescentic. Width of mouth nearly |- the width of head ; 

 praemaxillary band of teeth 4 times as long as broad ; teeth 

 on the palate obtusely conical, in two rather large subovate 

 patches which are not very widely separated anteriorly ; 

 maxillary barbel not quite reaching the base of pectoral. 11 

 gill-rakers on the lower part of the anterior arch. Dorsal I 

 6-7 ; spine a little less than ^ the length of head ; adipose 

 fin shorter than the dorsal. Anal 21-22. Pectoral spine § 

 or nearly § the length of head, with the inner edge rather 

 strongly seriated. Silvery ; back bluish grey ; fins more or 

 less dusky. 



Rio Ballena (Pacific Slope). 



Two specimens, 230 to 270 mm. in total length. 



This species differs from A. fuerthii.'m the longer head, 

 shorter barbels, shorter fin-spines, and more strongly serrated 

 pectoral spines. 



5. Rhamdia wagneri, Grtinth. 

 Rio Ballena. 



Cyprinodontidse. 

 6. Gambusia rhabdophora, sp. n. 



Depth of body 3| to 3| in the length, length of head 3| to 

 4. Snout as long as or shorter than eye, the diameter of 

 which is 3^ to 4 in the length of bead ; interorbital width 

 equal to the distance from middle of eye to free edge of 

 operculum. 27 or 28 scales in a longitudinal series. Dorsal 

 8-10 ; origin equidistant from end of snout and posterior 

 part or posterior edge of caudal fin. Anal 9 ; origin below 

 anterior £ of dorsal ; first branched ray the longest. Pectoral 



Ann. & Mag. N. Hist. Ser. 8. Vol. ii. 32 



