MONSTRILLA AND THE CYMBASOMATIDA. iu 
them, and must lead any observer to almost mistrust his 
eyes as did Claparéde—for how can it live with apparently 
no means of obtaining nutriment ? Its internal anatomy 
further bears out the supposition that its digestive powers 
must be very limited, for it is quite destitute of any 
alimentary canal; the small mouth discernable in some 
specimens opening directly into the body cavity. 
From the entire absence of mouth organs one would 
naturally surmise that the animal was a sucking parasite 
dependant for nutriment upon its host, and the cylindrical 
proboscis ending in a mouth possessed by some species 
lends countenance to this view. But against this it must 
be noted that this mouth is very rudimentary or entirely 
absent in the males of most of the species (they also being 
devoid of eyes) ; and further, as noted by Claparéde and by 
Bourne, all the specimens of Monstrilla hitherto recorded 
have been free swimmers near the surface. So there is 
no sufficient justification for the parasite theory, and for 
the present I am inclined to think with Bourne that 
‘“‘possibly this creature may present an analogy with the 
Ephemeride, and the adult may be preceded by a pre- 
daceous larva supphed with mouth parts and an alimentary 
tract, which, after a succession of rapid ecdyses, developes 
into the mature sexual form, whose only function is that 
of reproduction.” 
Bourne classifies the known forms of Monstrilla into six 
species : 
. Monstrilla rigida, 1. C. Thompson. 
. Monstrilla longispinosa, Bourne. 
. Monstrilla dane, Claparede. 
. Monstrilla viridis, Dana. 
. Monstrilla heligolandica, Claus. 
. Monstrilla anglica, Lubbock. 
Oo ork WOW WH FE 
