408 



veloped ; the scales are cycloid, and the tubes of the lateral line 

 branching. Ileckel separated the genera Cichla and Chromis, 

 and with the Scicenoids having less than seven branchiostegal rays, 

 formed a distinct family, the Chromids. Miiller found that the 

 first of these differed from the latter, which have no suture in the 

 last pharyngeal bone, and pseudobranchia on the inner surface of 

 the operculum ; he called the latter Pomacentrini ; for the former 

 he retained the name Chromids, uniting them, however, under 

 the name of Phcu-yngognathi, and including with them the genera 

 Belone, Scomheresox, and Exocetus, but which really are in no 

 way allied to the Labroids, Pomacentrini, and Chromids. 



Eveiy Labroid is a marine fish ; all the Chromids are inhab- 

 itants of fresh water, and peculiar to South and Central America, 

 except one species in the Nile, and one in South Africa. Of 

 the four genera from Nicaragua, one, were it not for the inter- 

 rupted lateral line, would reseinble very closely Dentex ; Prof. 

 Agassiz proposed to call it Parachromis gidosus. A second, re- 

 sembling Chrysophrys, he called Hypsophrys unimacidatns. A 

 third resembling Bodps, he named Baiodon fasciatus. The last 

 he called Amphilophus Froehelii, which is peculiar in not having 

 the ordinary fleshy lips, but a large triangular lobe projecting 

 above the upper and below the lower jaw, like the nasal append- 

 ages of some bats. 



Though the form of these Chromids varies from the elongated 

 shape of the Pickerel to the roundness of the Bream, there is one 

 character common to all — the second dorsal fin and the anal are 

 pointed backward, extending over the caudal. Though coming 

 from the same lake, and belonging to the same family, the disti'i- 

 bution of the colors varies considerably ; yet it is derived from 

 one pattern. Prof. A. showed how from the simple vertical bands 

 of the sides, a longitudinal line was formed by the increase and 

 union of the color in the centre of the bands, and its fading above 

 and below ; and how in the H. unimaculatus a single spot was 

 developed to the exclusion of the rest. 



Dr. C. T. Jackson exhibited some fine samples of to- 

 bacco, Nicotiana tabacum, raised in the Connecticut 

 valley, at Hatfield, Mass., by Mr. Dickinson. On drying 

 it, the specimens were found to lose 88 per cent, of their 



