20 



paratively short and more or less pronouncedly club-shaped, each ramus pro- 

 vided in female with only 3 distinctly developed setae, whereas in male, con- 

 trary to what is the case in Monstrilla, their number is generally increased by 

 one additional seta. Eye as a rule well developed. Antennae rather short in 

 female and only composed of 4 joints, in male much more elongate, and 

 distinctly 5-articulate, with a well-marked hinge between the last 2 joints. Oral 

 tubule generally occurring far in front, in close approximation to the frontal 

 part of the head. Natatory legs built in the usual manner. Last pair of 

 legs in female comparatively short, but provided inside with a well defined 

 lobe; in male wholly absent. 



Remarks.- Tins genus was proposed in the year 1888 by J. C. Thomp- 

 son, to include a peculiar Copepod (C. rigidum), of which at first only a 

 single female specimen was found. As, on a closer examination of several other 

 specimens taken by the same author partly in the Mediterranean, partly on the 

 British coast, the near relationship of this form to the species at that time 

 referred to the genus Monstrilla of Dana was recognised, the generic name 

 Cymbasoma was subsequently withdrawn in favour of that of Monstrilla. By the 

 subdivision of the latter genus into 2 nearly-allied genera carried out by Giesbrecht, 

 it was, however, of course required to decide to which of these 2 genera the species 

 of Thompson should be referred, and in this regard no doubt can arise. It 

 is quite certainly a true member of the genus to which Giesbrecht had applied the 

 name Thaumaleus. Since, however, as stated above, the application of this 

 name to the present genus is quite inadmissibel, I have felt justified to restore 

 the generic name proposed by Thompson. 



The genus here treated of is chiefly distinguished from Monstrilla by the 

 reduced number of segments in the tail, and, by the likewise reduced number 

 of caudal setae. Moreover the position of the oral tubule and the total 

 absence in the male of the 5th pair of legs may be named as characters di- 

 stinguishing the present genus. Three well defined species with be described 

 in the succeeding pages. 



