405 Part III. — Eighteenth Annual Report 



collection at Bay of Nigg. It measures about 20mm. from the extremity 

 of the rostrum to the base of the dorsal shield. 



Jaxea nocturna, Nardo. 



In my paper on Clyde tow-net and other gatherings published in 

 Part III. of the Seventeenth Annual Report (1899) I reported the 

 occurrence of an interesting lucifer-like crustacean in the Firth of Clyde. 

 I stated further that this crustacean had been identified with a form, also 

 from the Clyde, which had been described in the Proceedings of the Royal 

 Society, Edinburgh, vol. xv., p. 420, figs. 1 and 2 in the text (1889), by 

 the late George Brook under the name of Trachelifer. In some additional 

 remarks which immediately follow what had been stated in regard to 

 Brook's description of Trachelifer, it is clearly shown that this 

 " Trachelifer " was really the young of Calliaxis adriatica, Heller. 

 Nothing further transpired concerning these Clyde organisms till last 

 summer, when I received from Mr. F. G. Pearcey, the naturalist on board 

 the " Garland," a number of fragments of a small Nephrops-like crustacean 

 which he had found in the stomachs of some gurnards captured in the 

 vicinity of Ailsa Craig, near the mouth of the Clyde estuary. It was at 

 once evident that these fragments did not belong to Nephrops norvegicus, 

 though in some respects they had a more or less close resemblance to that 

 crustacean. The species, however, could not be made out for a consider- 

 able time. At first it was thought that the fragments might represent 

 one or other of the described species of Nephropsis, but with none of 

 these would they fit in satisfactorily. Failing, for various reasons, to 

 arrive at a satisfactory solution of the difficulty, I applied to the Rev. T. 

 R. R. Stebbing, who has not unfrequently proved in such matters to 

 be a "friend indeed;" and he, after some investigation, found that 

 the fragments which had given us so much trouble belonged to a species 

 which Nardo in 1847 had described under the name of Jaxea nocturna. 

 He, moreover, pointed out (as he does also iu his History of Crustacea, 

 p. 187) that Jaxea nocturna is identical with Calliaxis adriatica, Heller, 

 described in 1856 ; and as Trachelifer is the young of Calliaxis, so also, 

 as a matter of course, is it the young of Jaxea. The position of the 

 species may therefore be stated thus : — 



Jaxea nocturna, Nardo (1847). 

 = 1856. Calliaxis adriatica, Heller. 

 = 1889. Trachelifer, sp. (jun.), Brook. 

 Another point of interest that may now be considered is the habitat of 

 Jaxea. Can we claim it as a member of the Clyde fauna 1 In regard to 

 this point I am inclined, after a careful consideration of all the circum- 

 stances, to consider that we may fairly make this claim. We find these 

 juvenile forms occurring at more or less frequent intervals in various 

 parts of the Clyde area,* and occasionally in considerable numbers, two or 

 three different stages of development being represented, and latterly, as 

 pointed out, fragments of several adult specimens have been found in the 

 stomachs of gurnards caught in the vicinity of Ailsa Craig. From the 

 state cf preservation in which these fragments were found it is scarcely 

 likely that the time that had elapsed between the capture by the gurnards 

 of the specimens to which the fragments belonged and the capture of the 

 gurnards themselves in the " Garland's " trawl-net could have been very 

 great. All this seems to indicate that the adult Jaxea are not very far 

 off from the places where these larvae and fragments were obtained. It 



* Trachelifer was obtained in a bottom tow-net gathering collected at Station V. 

 (Whiting Bay) — a station well within the limits of the Clyde estuary— on October 11th, 

 1899. 



