236 THE ANATOMY OF INVERTEBRATED ANIMALS. 



appendages, each divided into two portions, an inner and an 

 outer. The latter is by far the larger, and is so constructed 

 that the three distal articulations can be bent back upon the 

 proximal ones, and opposed to the internal division, consti- 

 tuting a prehensile organ, the " hand " of Jurine. 1 Thus the 

 gnathites of Cyclops are a pair of mandibles followed by two 

 pairs of maxillas. At some distance behind the third pair of 

 gnathites the first pair of thoracic appendages is attached to 

 the hinder part of the cephalo-thorax. Each consists of a two- 

 jointed basal part {protopodite), terminated by two three- 

 jointed divisions (exopodite and endopodite). Three similar 

 pairs are appended to the three anterior free somites, while 

 a fifth rudimentary pair is connected with the next and small- 

 est of these somites. The suddenly-enlarged following seg- 

 ment of the body carries the apertures of the reproductive 

 organs in the female, and supports the ovisacs. It is com- 

 monly regarded as the first abdominal somite ; but, according 

 to Claus, it is composed of two distinct somites, which be- 

 come united only after the last moult. 



The alimentary canal is straight and simple, and without 

 any distinct liver. There is no heart nor any special respira- 

 torv organ. 



The single ovary, situated in the thorax, is provided with 

 two oviducts, which open on the sides of the coalesced first 

 and second abdominal somites. On the ventral face, between 

 the apertures of the oviducts, is the median aperture of a 

 colleterial gland which secretes the viscid matter which forms 

 the coat of the ovisac. Short lateral ducts connect the gland 

 with the extremities of the oviducts. 



The male is much smaller than the female, and the two 

 enlarged somites of the abdomen remain distinct. There ic 

 a single testis provided with two vasa deferentia. A special- 

 ly glandular portion of the latter secretes the material of 

 the spermatophores, or cases in which the spermatozoa are 

 inclosed. The antennae are thickened, and provided with a 

 peculiar hinge-joint, by means of which the male firmly 

 seizes the fourth pair of swimming-legs of the female during 

 copulation, and then, bending up his abdomen, deposits two 

 of the spermatophores on the median opening of the colle- 



1 That these are two divisions of the third gnathite, and not two separate 

 appendages, has heen demonstrated by tracing out their development. ( Claus, 

 " Organization und Verwandtschaft der Copepoden," Wi'irzburger natvrwus. 

 Zeitschrift, 1862.) Under these circumstances I do not know why they should 

 be termed " maxillipedes." 



