Rev. T. E. R. Stebbing on Gastrosaccus spiniferas. 117 



The outer laminae are rather shorter than the inner, with 

 twelve long incurved spines on the outer side ; the truncated 

 end and the inner sides are adorned with very long plumose 

 setee. The telson and uropods are semitransparent, displaying 

 all over a fine honeycomb pattern. 



This little species I found last August (1879) at Banff, 

 while turning up thin slices of sand at low tide in search of 

 sessile-eyed crustaceans. I had proposed to name it in honour 

 of Professor G. 0. Sars, whose finely and fully illustrated 

 monograph on the Mysidae has set forth the group with a 

 clearness, both of writing and figuring, quite in keeping with 

 the delicate transparency of the animals described ; but the 

 Rev. A. M. Norman, from figures which I sent him of the 

 spined dorsal sinus, identified it with the Gastrosaccus sanctus 

 of his Shetland Dredging Report, 1868. That species is de- 

 scribed as equivalent to Mysis spinifora of Goes, and as 

 having the dorsal sinus " elegantly scalloped." This expres- 

 sion did not, in the first instance, represent to my mind the 

 spine-like ornamentation of the carapace already described. 

 I was fortunate, therefore, in being able to obtain Mr. Nor- 

 man's own interpretation of it. It is curious that Goes makes 

 no remark upon this striking characteristic. In other 

 respects my specimens tally so closely with his description 

 and Mr. Norman's, that I should not feel justified in putting 

 forward a new name for the species. The only point that 

 might raise a doubt is, that both the authors named are 

 inclined to identify the species they have in view with the 

 Mysis sancta of Van Beneden, whereas that author figures the 

 fifth abdominal segment of his species without the very spine 

 which gives its name to Gastrosaccus spiniferus. Van Bene- 

 den leaves the description of his species almost a blank ; and 

 the figures which he gives might, quite within the bounds of 

 possibility, roughly represent the corresponding parts of three 

 or four different species*. All that can be said is that they do 

 not disagree with the Gastrosaccus sanctus fully and minutely 

 described and figured by Sars, while they present one essen- 

 tial point of distinction from the description by Goes of Mysis 

 spinifera. 



* On my submitting the question of nomenclature to Monsieur van 

 Beneden himself, he replied, with courteous promptitude, that for a deci- 

 sion it -would be necessary to compare the actual specimens described 

 both with one another and with a series of others of various ages and 

 both sexes. In the absence of means for doing this, he inclines to Mr. 

 Norman's view, which, as I have stated above, was to unite G. sandtis 

 and G. spiniferus. 



Ann. & Mag. N. Hist. Ser. 5, Vol. vi, 9 



