245 Part III — Twenty-second Annual Report 



The following are the localities whence I have obtained this species 

 and the dates when the different specimens were collected : — 



Firth of Forth, between Fidra and the Bass Eock, October 18, 



1890 ($). 

 Firth of Forth, east of Inchkeith, August 14, 1891 ($ & tf)« 

 Firth of Forth (locality not stated), 1893 ($ & rf). 

 Firth of Forth, Station V. (to the west of May Island), August 30, 



1894 ($ &tf). 



Firth of Forth, Station V., July 24, 1901 ($). 



Firth of Tay, at Buddon, December 5, 1902 ($). 



Thirty-five miles east of May Island (per s.s. "Glenogle," of 



Aberdeen), August 20, 1903 ($ & tf). 

 Off Aberdeen about ten miles, November 11, 1901 ($). 

 Firth of Clyde, off the Ayrshire coast, November (date not stated), 



1895 ($). 



Firth of Clyde, head of Loch Fyne, December 11, 1897 ($). 

 Firth of Clyde, Whitefarland Bay, Arran, July 6, 1899 (tf). 

 Solway Firth, Luce Bay (per Andrew Scott), November 26, 1901 ($). 

 Larne Harbour, Ireland (per Andrew Scott), January 14, 1904. 



The female represented by the drawing (fig. 1) measured 3T mm., 

 which is similar to the size given by Dr. Giesbrecht ; the length of the 

 male which the drawing represents (fig. 2) is 2 mm. 



One or two of the more obvious characters by which M. longicornis 

 may be distinguished from other forms are the long and somewhat slender 

 antennules, the form and armature of the fifth pair of thoracic feet, 

 and the number of the f ureal setae. The structure of the abdomen 

 appears also to differ to some extent from the other species of Monstrilla 

 recorded here. 



It may be remarked further that the integument in this species when 

 examined with the microscope and under a moderately high power is seen 

 to have a granular appearance not observed in other species (see the 

 drawings, figs.l and 2). 



That I. C. Thompson's Monstrilla longicornis is identical with M. 

 longiremis, Giesbrecht, must, I think, be admitted. The long antennules, 

 the granular appearance of the integument, the number of f ureal setae, and 

 the structure of the abdomen show that it can be nothing else, and as 

 Thompson's name was published two years before that of Dr. Giesbrecht 

 it must be restored. Thompson does not appear to have seen the female 

 or Dr. Giesbrecht the male of this species. 



Monstrilla gracilicauda, Giesbrecht. PL xiii., fig. 8-10; pi. xiv., fig. 15. 



1892. Monstrilla gracilicauda, Giesb., op. cit., p. 587, pi. 46, 

 figs. 9, 16, 18, 29, 32, 43. 



In the female of Monstrilla gracilicauda the antennules are rather 

 shorter than in the species just described. They appear to be four- 

 jointed, the first three being small, while the end joint is equal to the 

 entire length of the other three (fig. 8, pi. xiii.). 



The fifth pair of thoracic feet (fig. 15, pi. xiv.) are sub-quadrate in out- 

 line, rather longer than broad, and somewhat gibbous at the distal end as 

 shown in the drawing ; each foot is furnished with three plumose setae, 

 one on the outer aspect and two at the apex, the feathering is very 

 delicate and can only be seen by using a moderately high magnification. 



The abdomen consists of four segments, the first segment, which 



