Introduction to Animal Morphology. 347 



hinder the mandible and maxillipede. The post ab- 

 domen bears a fringe of bristles, and often is split into 

 rudder-like processes ; many are acardiac. 



Two orders are included : 



i. Gnathostomata free, minute, marine, or freshwater, 

 with developed jaws, and a moderate post-abdomen. This 

 includes two families: i. Cyclopidae first pair of anten- 

 nae long, oar-like, with (on the right only, Diaptomus) 

 thickened clasping joints in the male ; the female carries 

 two (one in Diaptomus and Canthocamptus) lateral egg- 

 sacs ; eye either median (Cyclops, Diaptomus) or paired 

 (Cetochilus, Sapphirina). The male Sapphirina is luminous. 

 Cetochilus sometimes dyes the sea a deep red. Monstrilla, 

 Calanus, Pontella, and Corycaea are often made types of sub- 

 families. 2. Notodelphidae parasites in the branchial sacs 

 ofAscidians; body 11-12 ringed; in the females the fourth 

 and fifth metameres are united, forming a brood-sac for the 

 eggs ; maxillae many-cleft ; first abdominal ring joined to the 

 cephalothorax. 



Order 2. Siphonostomata Fig. 39. 



(LatreMt} adults ecto-para- 

 sitic on fish, with suctorial 

 mouths, soft bodies, and 

 retrogressive metamorphosis ; 

 jaws reduced to bristles ; thorax 

 imperfectly or not segmented ; 

 front feet hook- or sucker-like ; 

 the males are often pigmy, and 

 the females usually carry their 



eggS, like Cyclops, in two Cyclop quadrirornis. with it 



sacs. They include the fol- 

 lowing families: r 'uh,- passage forms, the females 

 only parasitic ; body thick ; antennae joint. -d and bristled ; 

 second pair clawed ; post-abdomen jointed, \\ith bristle-bear- 

 ing tail ; abdominal feet rnnovcd from (lie medial line ; the 

 males in Nicothoe, &c., arc Cyclops-like, and in the female 

 (a lobster parasite) the abdomen forms on cadi side a long 

 lateral sac, and the egg cl; between these. 'I'he 



