MONSTRILLOIDA. 



Remarks.- The most prominent morphological character distinguishing 

 this group of Copepoda, is the total absence, in the adnlt state, of both 

 the posterior antennae and of any traces of oral appendages, as also of a 

 functional alimentary canal. Of course the fully developed animal is quite 

 incapable to feed in the ordinary manner, but may only subsist on the 

 nourishing matter accumulated within the body-cavity during its juvenile 

 parasitic existence, the adult stage being exclusively devoted to the propagation. 

 The division Monstrilloida comprises as yet only a rather restricted number of 

 forms, which all formerly were referred to a single genus, viz., Monstrilla of 

 Dana, with which the genus Thanmaleiis of Kreyer was considered to he- 

 identical. In recent times, it is true, a subdivision of the genus Monstrilla 

 into 2 or 3 genera has been attempted, but these genera are so closely allied, 

 that they at all events must be comprised within the same family. Yet an 

 interesting new genus (Thaumatopsyllus), apparently referable to the Monstril- 

 loida, has recently been added by the present author, and this genus is so 

 very different from the other Monstrilloid genera, that it cannot by any means 

 be included in the same family with them, but must be regarded as the type 

 not only of a separate family, but even of a distinct section, for which I have 

 proposed the name Monstrilloida cyclopimorpha. Of course the division 

 Monstrilloida appears at present cleft into 2 well defined sections, the M. 

 cyclopimorpha and the M. gennina; but each of these sections is as yet only 

 represented by a single family. 



