NO. 1573. PARASITIC COPEPODS— WILSON. 461 



all represented with rami having but a single joint. This species, 

 therefore, like the others, can not be located with any reasonable 

 probability. 



NOGAGUS VALIDUS Dana. 



Nogagus validus Dana, 1852, p. 1863, i>l. xciv, figs. 9a to h. 

 The male of Pandarus hrevicaudis (see p. 398). 



Part 4.^THE CECROPIN^E. 



ECOLOGY. 



This new subfamily is made to include at the present time four 

 genera which closely agree with each other in habits and morphol- 

 ogy, and which differ very markedly from the genera included in 

 the PandariiiiB. As the latter were shark parasites, so the present 

 genera may be said to belong to the family of Head-fishes or Sunfish 

 (Molida>), although they are occasionally found on other fish. Two 

 of the genera are so closely confined to the common Sunfish (Orthra- 

 goriscus, or Mola, mola) that they have been given generic names 

 derived from that of their host, Orthagoriscicola and Philorthragoriscus , 

 respectively. 



A third genus, Cecroys, makes the sunfish its chief host, but has 

 been found also on species of Diodon, Tliynnus, and Pleuronectes , 

 while the fourth genus, Luetkenia, lives upon Asterodermus , Luvarus 

 and several shark species. 



These pasasites are more gregarious than the Pandarinte and are 

 found in bunches of fifteen to thirty or more, attached to the outside 

 skin and gills of the fish. The combined laceration of their claws 

 often produces a large pit or sore, in the bottom of which they cling 

 tightly. This peculiarity has been noted by A. Scott (1892, p. 266), 

 who describes Ortliagoriscicola as burrow^ing in pits formed in the 

 flesh of the fish behind the anal fin. Nothing of this sort is found 

 among the Pandarinse for two reasons — first, they do not collect in 

 such numbers, and then they cling partly- if not chiefly by means of 

 their adhesion pads. Hence when several of them do get together, 

 as often happens on a shark's fin, there is very little laceration and 

 no bunch or sore is formed. 



Not only the females of the present subfamily, but the males as 

 well remain fixed in one position upon their host, and both sexes are 

 incapable of swimming. As already noted (see p. 327), this constitutes 

 the last step in degeneration as exhibited in the Caligidge. The 

 female became a fixed form in one of the Caliginne (Echetus), in sev- 

 eral of the Euryphorinse, and in all the Pandarinse, but the progress 

 of degeneration was very slow, and the swimming legs were retained 

 in their normal form and armed with plumose setae through all the 



