SOME NOTES ON THE SCOTTISH CRANGONID^ 227 



The rostrum is moderately broad at the base, but tapers towards the 

 apex, which is rounded. The carapace, or shield, is comparatively 

 smooth, and is furnished in front with three moderately prominent 

 spine-like teeth, one on each side, and one in the middle behind the 

 rostrum ; the three teeth are nearly in line, but the middle one is 

 slightly posterior to the others. The remaining segments are smooth 

 and evenly rounded on the dorsal surface, except that in some 

 specimens there is a slight flattening or depression along the middle 

 dorsal aspect of the last segment. The colour is usually a " speckled 

 grey." One of the largest specimens, with ova, in our collection 

 measures 70 millimeters from the point of the rostrum to the 

 extremity of the " tail " ; but larger specimens may sometimes be 

 observed. 



Crangon Allmanni, Kinahan. — This is also a common species, 

 and is perhaps as common and generally distributed as the last, but 

 being confined to deeper water is not as frequently noticed by the 

 casual observer. It has a moderately close resemblance to C. 

 vulgaris, but scarcely attains so large a size. The carapace, as in 

 vulgaris, is comparatively smooth, and has similar spine-like teeth in 

 front ; the remaining segments are also smooth, except that in the 

 last one there is a distinct groove bordered on each side by a 

 prominent ridge which extends the whole length or nearly so of its 

 dorsal aspect. Moreover, the rostrum is not only distinctly narrower, 

 but it is more cylindrical ; the specimens are also usually of a 

 brownish colour rather than grey. The largest ova-bearing speci- 

 mens in our collection range from 55 to 58 millimeters in length 

 from the point of the rostrum to the end of the tail. 



Crangon trispinosus {Hailstone). — This species resembles in 

 some respects a small Crangon vulgaris, especially in the armature 

 of the carapace, or shield, but the colour is somewhat different, and 

 so also is the form of the rostrum. In this species the rostrum is 

 comparatively short and broad, it sides are nearly parallel, and the 

 apex, instead of being rounded, is subtriangular. Moreover, the 

 arrangement of the three spines on the front of the carapace is 

 somewhat different from that usually observed in Crangon vulgaris, 

 in which species the middle spine is slightly posterior to those at 

 the sides, while in C. trispinosus the two side spines are slightly 

 posterior to the middle one — a difference readily noticed if one 

 looks across the back of the specimen ; the same difference is 

 observable between C trispinosus and C. Allmanni. The abdominal 

 segments are all comparatively smooth, and evenly rounded on the 

 dorsal aspect, but a shallow groove extends along the middle of the 

 proximal half of the telson, or middle tail-piece. A female with 

 ova taken in Aberdeen Bay measured about 26 millimeters from the 

 extremity of the rostrum to the end of the telson. 



I have examined specimens of C. trispinosus from the Firth of 



