Dr. A . Giiuther on new American Fishes. 231 



25. MiCRODESMUS Dipus, D. g. ct sp. Of ihis we have re- 

 ceived only a single small example ; and as it is not in a perfect state 

 of preservation, we cannot decide whether it should be referred to 

 the Blennoids or Gadoids, or whether it is the type of a distinct 

 family. However, we may hope that Capt. Dow will succeed in ob- 

 taining more specimens. 



MiCRODESMVS. 



Body much elongate, eel-like, covered with rudimentary scales ; 

 head rather short, with obtuse snout, narrow cleft of the mouth, 

 and prominent lower jaw. Eyes minute. Teeth in both jaws mi- 

 nute ; palate toothless. The gill-opening is reduced to a small slit 

 in front of the pectoral fin. Vertical fins united by a membrane, 

 but the caudal can be easily distinguished from the two other fins. 

 Dorsal fin very long, composed of flexible, undivided rays, like the 

 anal. Pectorals short ; ventrals thoracic, each reduced to a single 

 raj. Vent in the middle of the total length. 



MiCRODESML'S DIPUS. 



D. 55. A. 3-1. C. 16. P. 12. V. 1. The depth of the body 



is about one-eighteenth of the total length ; the length of the head 

 one-eleventh. The head is rather compressed, the snout short, the 

 mouth very narrow, and the lower jaw very prominent. The mi- 

 nute eye is lateral and in the anterior third of the length of the head. 

 The dorsal fin commences at a distance from the occiput which is 

 somewhat less than the length of the head ; it is nearly even, and 

 the rays are very distinct, the interradial membrane being thin and 

 transparent. The anal fin commences immediately behind the vent. 

 The caudal rays are much more slender and more closely set than 

 those of the dorsal and anal ; the caudal fin is rounded, two-thirds 

 of ihe length of the head. Pectorals as lone as the ventrals, and 

 half as long as the head ; the latter fins are close together, and in- 

 serted a little behind the root of the pectoral. Upper parts uniform 

 brownish olive. 



The single specimen is 4|^ inches long. 



26. Anableps Dovii, Gill. 



II. Species collected at Colon. 



1. Pristipoma melanoptervm. Cut. & Val. 



2. PoMACANTHUS Paru, Gthr. 



3. Sphyr^na Picuda, B1. Schn. 



III. Species from the Lake of Managua, Nicaragua. 

 1. Heros labiatvs, n. sp. 



D. I^. a. |. L. lat. 32. L. transv. 6/13. The anterior por- 

 tions of the upper and lower lips are much enlarged, each forming a 



