332 MR. R. COLLETT ON CERTAIN GOBIOID FISHES. [Mar. 5, 



year, been mentioned, but without any accurate description, and 

 under the temporary name of Gobius linearis, by the same author 

 in a letter which was published in GEfv. Kgl. Vet. Akad. Forh. 

 May 1844. In Giinther's • Catalogue,' vol. hi. (1861) it is placed 

 under the genus Gobiosoma, although the correctness of this is 

 doubted. As early as in 1863 Prof. Gill (Proc. Acad. Nat. Sci. 

 Philad.) established for this species a new generic name, Crystallo- 

 gobins. Synonymous herewith is the name Latrunculodes, by which, 

 in 1874, not knowing the remarks of Prof. Gill, I entered it in a 

 treatise on the Gobioid Fishes of Norway (Forh. Vid. Selsk. Christ. 

 18/4), and later in the same year in a paper on the Fishes of Norway 

 (Supplementary part of the Forh. Vid. Selsk. Christ.). 



Since the species was entered in the system in 1874, it has not 

 been the subject of detailed description. Nilsson, in his ' Skan- 

 dinavisk Fauna' (1855), has taken his description from that of 

 Diiben and Koren, as is also the case with the few other authors 

 who mention the species. 



The same applies to this species as to Latrunculus pellucidus, that 

 the characters mentioned in the descriptions only belong to one of 

 the sexes, in Crystallogobius nilssonii to the fully developed male. 

 The female of this species, which shows a constant and remarkable 

 difference from the male, has not hitherto been described. 



In June 1875 I found the species in the Christiania Fjord in mature 

 state, together with Latrunculus pellucidus, though in very much 

 smaller numbers ; and more lately I have on a few occasions collected 

 young specimens out of the spawning-season. Although the number 

 of specimens which at present stand at my disposal, namely 33, do 

 not represent an unbroken series of all the different ages of both 

 sexes, I can still give a descriptive account of their principal stages. 



B. General Description. 



The mature males have a total length of between 43 and 47 

 milllims. ; still maturity is evidently attained in some specimens 

 with a length of 38-40 millims. The first dorsal fin has long rays 

 with a wide membrane ; the head is thickened, with a short snout ; 

 the jaws long, and singularly bent towards each other; the canine 

 teeth in the lower jaw high and curved ; and the intermaxillary 

 bones form on each side a strong projection, almost in the form of 

 a nail. A little more pointed is the head, and the body on the 

 whole is more slender, in the males which have not reached a total 

 length of 70 millims ; neither have the jaws nor the teeth in this 

 case attained their full length, though the testicles are filled with 

 ripe milt. 



The young males, whose testicles do not yet contain ripe milt, 

 although their total length is only a trifle less than the smallest of 

 the mature specimens, namely 36 millims., have the body thin and 

 slender, the head pointed, almost as in the females ; the teeth, 

 however, are already visible, and all the fins normally developed. 



The mature females, with the eggs ready for spawning, are con- 

 siderably smaller, and of a more slender construction, than the 



