GILBERT AND ST ARKS — FISHES OF PANAMA BAY 117 



much reduced in size. The base of the spinous dorsal is two-thirds (not nearly equal 

 to) the length of the soft dorsal or anal. The soft dorsal contains 15 (not 13) rays. 



Family SCI^NID^. 



217. Isopisthus remifer Jordan & Gilbert. 



Abundant; known only from Panama. This species is probably distinct from 

 its very close Atlantic rej^resentative, /. parvipinids, but no specimens of the two 

 have been directly compared, and the characters alleged to distinguish them are in 

 need of verification. /. remifer is said to have longer pectoral fins and more numer- 

 ous rays in the anal fin. In seven specimens at hand, however, the pectoral is 

 shorter than the description of the type would indicate, equaling the length of the 

 head behind the front of the pupil, and contained 1^- to If in the length of the head. 

 They agree in this character wholly with the type of I. parvipinnis (see Jordan, 

 1883, p. 289), and with its synonym /. affinis Steindachner. /. remifer is said to 

 have 19 rays in the anal, as contrasted with 16 or 17 in parvipinnis. The only reli- 

 able information concerning the condition in parvipinnis is derived from Steindach- 

 ner's description and figure of /. affinis. In two specimens examined by him, the anal 

 fin contained 16 and 17 rays. In seven specimens of I. remifer, the anal counts are 

 as follows: 16, 17, 17, 18, 18, 18, 18. In the type of remifer, there are said to be 19 

 rays. It is impossible to pronounce upon the distinctness of these two species until 

 adequate Atlantic material is at hand for comparison. 



The dentition has been insufficiently described by all observers. It differs in 

 no essential respect from that characteristic of Oynoscion. The mandible contains 

 an outer series of minute teeth, closely associated with an inner sei'ies of elongate 

 canine-like teeth of considerable size. The canines are not definitely 3 in number, 

 as described by Steindachner, but vary from 6, the normal number, to 2 or 3, the 

 missing ones having become accidentally detached. The canines are largest along 

 the middle of the side of the mandible, and cease before reaching the symphysis, the 

 tip of the mandible being occupied by a double series of very small teeth. On the 

 sides of the upper jaw is an outer row of slightly enlarged teeth, and a narrow band 

 of villiform teeth behind it. Anteriorly the band disaj^pears and gives place to a 

 short inner series, the median pair of which are enlarged to form the very conspicuous 

 fangs. 



The scales agree in size in the two species, there being 52 to 55 enlarged 

 scales along the lateral line, and above the lateral line 70 to 75 oblique series running 

 downward and backward. 



Isopisthus seems to differ inadequately from the genus Archoscion, being dis- 

 tinguished only by the longer interval between the dorsal fins. 



(16) December 4, 1903. 



