The Blennies: Blenniidas 527 



an elaborate series of venom glands connected with the hollow 

 spines of the opercle and the dorsal spines. Dr. Gunther gives 

 the following account of this structure as shown in Thalasso- 

 phryne reticulata, a species from Panama: 



"In this species I first observed and closely examined the 

 poison organ with which the fishes of this genus are provided. 

 Its structure is as follows: (i) The opercular part: The oper- 

 culum is very narrow, vertically styliform and very mobile ; it is 

 armed behind with a spine, eight lines long in a specimen of io 

 inches, and of the same form as the venom fang of a snake; it 

 is, however, somewhat less curved, being only slightly bent 

 upward. It has a longish slit at the outer side of its extremity 

 which leads into a canal perfectly closed and 'running along 

 the whole length of its interior; a bristle introduced into the 

 canal reappears through another opening at the base of the 

 spine, entering into a sac situated on the opercle and along the 

 basal half of the spine ; the sac is of an oblong-ovate shape and 

 about double the size of an oat grain. Though the specimen 

 had been preserved in spirits for about nine months it still con- 

 tained a whitish substance of the consistency of thick cream, 

 which on the slightest pressure freely flowed from the opening 

 in the extremity of the spine. On the other hand, the sac could 

 be easily filled with air or fluid from the foramen of the spine. 

 No gland could be discovered in the immediate neighborhood 

 of the sac; but on a more careful inspection I found a minute 

 tube floating free in the sac, whilst on the left-hand side there 

 is only a small opening instead of the tube. The attempts to 

 introduce a bristle into this opening for any distance failed, 

 as it appears to lead into the interior of the basal portion of the 

 operculum, to which the sac firmly adheres at this spot. (2) The 

 dorsal part is composed of the two dorsal spines, each of which 

 is ten lines long. The whole arrangement is the same as in 

 the opercular spines; their slit is at the front side of the point; 

 each has a separate sac, which occupies the front of the basal 

 portion; the contents were the same as in the opercular sacs, 

 but in somewhat greater quantity. A strong branch of the 

 lateral line ascends to the immediate neighborhood of their base. 

 Thus we have four poison spines, each with a sac at its base ; the 

 walls of the sacs are thin, composed of a fibrous membrane, 



