1878.] MR. R. COLLETT ON CERTAIN GOBIOID FISHES. 337 



tendency to division of the rays is characteristic of this species as 

 compared with Latrunculus pellucidus, in which division of the rays 

 takes place especially in the ventral fins. The funnel is comparatively 

 short ; when closed it is, even in the male, removed from the vent 

 to a distance about equal to its own length. In young males the 

 ventral fins are very small, and their funnel-like shape is almost 

 imperceptible, the connecting membrane being incomplete. 



In the female the ventral fins are completely rudimentary, being 

 only present as a couple of two disconnected and very short rays 

 scarcely the diameter of the eye in length. 



The mucous glands, which in L. pellucidus form so extensive a 

 system, seem to be almost entirely wanting in Crystallogobius nils- 

 sonii ; in none of the specimens which I have examined have I 

 been able, with certainty, to find a single complete row of such 

 glands, either on the head or on any other part of the body. 



The skin. — No trace of scales has hitherto been detected in 

 any of the specimens examined. As is the case in L. pellucidus, 

 the whole side of the body shows a row of transverse impressions ; 

 when examined in the microscope, no trace is found of follicles to 

 which lost scales may have been attached ; and it is therefore 

 scarcely to be doubted that the body is altogether naked in this 

 species. The number of these muscular impressions is twenty-seven, 

 twenty of which have their place behind the vent ; they bend to- 

 gether into the form of an angle in the middle line of the body, and 

 denote exactly the number and size of the vertebrae. An actual 

 lateral line, with open pores, does not exist. 



The colour. — As is the case in L. pellucidus, the body during 

 life is transparent, with a faint bluish tinge, thereby enabling the 

 vertebrae, the applejof the eye, &c. easily to be seen. The colora- 

 tion of the skin is very faint, and does not vary in this respect to 

 any degree, even during the spawning-season. The eyes are strongly 

 coloured, their upper edge being of a shining metallic lustre (black 

 after death) ; the iris is silvery. A well-defined blackish spot is 

 found at the point of the lower jaw ; another black stripe stretches 

 along the throat towards the ventral fins. At the root of each 

 ray in the anal and the caudal fin there is a black point ; these 

 together form a continuous and distinct row, which is present in 

 both sexes and at all ages; along the dorsal fin there is found a 

 somewhat fainter row of brownish points, which is indistinct, or 

 nearly wantiug, in the female. Moreover all the rays are covered 

 with minute blackish points. The body itself is almost unspotted 

 (whitish when preserved in spirits), except on the sides of the belly, 

 where a row of fine brownish spots stretches itself ; these spots are 

 largest and most distinct in the breeding female, their number being 

 3-5 on each side. 



C. Habits and Distribution. 



Generation. — With regard to the time of breeding and its dura- 

 tion, nothing conclusive can be said at present on account of the very 

 Proc. Zool. Soc— 1878, No. XXII. 22 



