EDWIN CHAPIN STARKS 31 



only a fine line of naked skin between. Occasionally the space is a little 

 wider, but in none is it as wide as in the picture. 



99. Doras dorsalis Cuvier and Valenciennes. 



Many specimens of this common species were collected at Para. In 

 most of them the stomach was tightly filled with a small univalve shell. 



The dorsal median plates and the ventral plates on the caudal peduncle 

 are apparently never present in specimens as small as 5 inches in length, 

 but in those 6 inches long some of them are present at least as rudiments. 

 Though they are usually the best developed in the largest specimens they 

 may be almost entirely absent. There is also much variation in the rough- 

 ness of the head. In one specimen the bones of the head are so finely 

 granular as to appear almost perfectly smooth. 



These specimens show some slight variations from Dr. Eigenmann's 

 description (S. Am. Nematog. Cal. Acad. Sci.,1890). The caudal peduncle 

 measured at the bases of the spines is as wide as deep. Usually a series 

 of slight broken ridges extends from the frontal to the dorsal plate, and a 

 well-developed groove on the dorsal plate extends to its tip, but only oc- 

 casionally "a marked groove extends form it [the frontal] to the tip of the 

 dorsal plate." The pectoral spine is as long as the dorsal spine or often a 

 trifle longer, and in the young of 6 inches in length it is equal in length 

 to the head, or slightly shorter, but in specimens 10 or 11 inches in length 

 it is considerably longer than the head. 



100. Centromochlus heckelii (Fillppi). 



Several specimens of this peculiar little species were taken at Para, the 

 largest 4 inches in length. 



101. Trachycorystes galeatus (Linnaeus). 



Several specimens were collected in the market at Para. The follow- 

 ing color notes were made from fresh specimens. The ground color is 

 opaque, soiled light yellow, usually with black blotches scattered over the 

 head, body and fins. These may be absent or often take the shape of hori- 

 zontal elongate spots, or the form of irregular lines suggesting penciled 

 lines. The under parts are milk-white, often more or less soiled with groups 

 of small dark dots. 



102. Trachycorystes striatulus Steindachner. 



A few specimens were collected in the little ponds about Ceara Mirim. 

 These much resemble Trachycorystes galeatus, but the head' is not so rough 



