NATURAL SCIENCES OF PHILADELPHIA. 



55 



pit or fovea at the summit of the head is uot mentioned by Kii- 

 chenmeister and subsequent observers as a character of that spe- 

 cies. It is a point, however, that might be readil}^ overlooked, 

 especially if the parts of the head are obscured by'the presence 

 of pigment-granules. 



Fig. 1. 



a. Head and neck magnified. L Form of segments in an anterior fragment of the 

 worm. c. Form of segments in an intermediate fragment of the body. d. Form 

 of segments at the posterior part of the worm. 



Prof. Cope exhibited a number of fishes from the Amazon 

 above the mouth of the Rio Negro, which included some new and 

 rare forms. Some of the latter were Doras brachiafus, Plecostn- 

 mus scoiyularnis^ Roehoides rubrivertex^ Myletes albiscopus, etc. 

 The Plecostomus has the following characters: I). I. 7 ; A. 5 ; L.l. 

 27; head 25, total length; eye 25, interorbital width. Interaper- 

 cular bristles very short, acute. Dorsal fin longer than high ; 

 eight scuta between the first and second dorsals. Length, two 

 feet. Color, light brown, with very numerous closely placed 

 brown spots, those on the head more closelj' placed and often 

 vermiform. Dorsal fin spotted. Long bristles on front and outer 

 surfaces of both pectoral and caudal supporting rays, which are 

 hooked at the end. Caudal marginal radii subequal. No ridge in 

 front of orbit ; a short, prominent supra-occipital crest. 



He exhibited a specimen of Fariodon microps^ Kner, describing 

 the parasitic habits of Stegophilv.s and those ascribed to VandelUa. 

 He thought the structure and coloration of the Fariodon indi- 

 cated similar habits, and that it would be found to be an inhabi- 

 tant, at times at least, of the cavity of the body of some other 

 animal. 



March 28. 



The President, Dr. Ruschenberger, in the chair. 



Twenty-three members present. 



Mr. Joseph Wharton remarked that a letter, received this day, 

 from Thomas Macfarlane, the discoverer of Silver Islet, in Lake 



1871.] 



