COPEPODS OF THE WOODS HOLE REGION 11 



ilies. A little later (1901) Sars in his work on the Crustacea of 

 Norway began to present the Calanoida. When he finally com- 

 pleted the group by a supplement issued in 1919, he had included 

 43 genera and had divided them into 24 families. In comparison 

 with Giesbrecht and Schmeil, two-thirds as many genera were 

 divided into five times as many families. The differences in the 

 family grouping proposed by any other two authors might not be 

 so great as this, but no two systematic papers have thus far appeared 

 in which there was any agreement as to the numbers or limitations 

 of the families. Every author, however, is practically agreed as 

 to which of the eight suborders any given genus ought to belong. 

 For the present therefore it would seem to be wise to emphasize this 

 primary division into eight suborders and to place much less stress 

 upon the secondary division into families. Especially would it be 

 unwise to attempt any serious change in the family limitations or 

 to introduce any new arrangement of the family groups. The 

 family names here used are suggestive of what seems most rational 

 in the recent systematic discussions of the copepods, without any 

 attempt to fix their exact limitations. 



Suborder ARGULOIDA 



Fourth or last pedigerous segment firmly attached to the third 

 but forming a movable articulation with the fifth segment. Head 

 fused with the first segment and covered with a carapace, which is 

 expanded on each side into a broad lobe. Second, third, and fourth 

 segments free, each together with the first segment bearing a pair of 

 biramose swimming legs; fifth and sixth segments fused with the 

 abdomen without any trace of segmentation or swimming legs. This 

 fused urosome is notched or bilobed posteriorly and bears a pair 

 of caudal rami. The head bears two large compound eyes, which 

 are movable and surrounded by a blood sinus. Each lateral lobe 

 of the carapace contains two respiratory areas, sometimes fused, 

 sometimes separate, whose arrangement and shape are peculiar in 

 each species and thus afford a good specific character. First an- 

 tennae transformed for prehension and armed with curved claws; 

 second antennae uniramose; second maxillae also transformed into 

 prehensile sucking disks, except in the genus Dolops. A well-defined 

 heart with a short aorta and a definite blood circulation. Fertiliza- 

 tion not accomplished by spermatophores, and eggs not carried in 

 external ovisacs but fastened in rows to foreign objects. 



Remarks. — Tlie genus Argulus is the only one of the Arguloida 

 found in North America ; it is entirely parasitic, usually upon fish, 

 and may be obtained in fresh, brackish, or salt water. As yet no 



