NOTES ON THE GENUS MONSTRILLA. 575 
obtuse process in the same situation furnished with a pair of 
short foliaceous lappets. Two simple eyes and a third simple 
eye below. Mouth situated on a conical process on the ventral 
surface of the cephalon, leading into a short pharynx; the 
remainder of the digestive tract aborted. 
A. Three sete on each furcal member. 
1, Monstrilla rigida, I, C. Thompson. Cymbasoma 
rigida, I. C. Thompson (‘ Proc. Linn. Soc.’). 
Two abdominal segments, the first twice as long as the pre- 
ceding thoracic segment, swollen, bearing two genital setz, 
which do not extend far beyond the furcal sete. Hab. 
Madeira, Plymouth, Channel Islands. 
2. Monstrilla longispinosa, nov. sp. 
Two abdominal segments, the first of equal length to the 
preceding thoracic segment, and provided with a genital seta, 
single at its origin, bifurcating behind the furca, and more than 
half as long again as the whole animal. Fifth thoracic ap- 
pendages of the female short, with the endopodite shorter than 
the exopodite. Hab. Plymouth. 
3. Monstrilla Dane, Claparéde (‘ Beobacht. iiber Anat. u. 
Entwick.,’ &c., p. 95. 
Three abdominal segments, the first bearing two genital 
sete. Body elongate, narrowed. Hab. Cherbourg, Plymouth, 
Channel Islands. 
B. Six setze on each furcal member. 
4. Monstrilla viridis, Dana (Dana, ‘ Proc. Amer. Acad.,’ 
li, p. 52). 
Four abdominal segments ; buccal cone in the centre of the 
cephalothorax. Hab. Sulu seas, Zamboanga. 
5. Monstrilla helgolandica, Claus (‘ Freileb. Copep.,’ 
p- 165). Cymbasoma rigidum, Scott (‘Seventh Ann. 
Report, Fishery Board for Scotland,’ p. 316). 
Four abdominal segments. Antennz four-jointed, the two 
last joints elongate, subequal. The protopodite of the swim- 
ming feet bears a spine on its interior lower angle. Hab. 
Heligoland, Firth of Forth. 
