NO. 2194. NORTH AMERICAN PARASITIC COPEPODS— WILSON. 45 



in the Chondracanthidae, while Clans (1858) was the first to recog- 

 nize it as a Lernaean. Kr0yer (18G3) added two new species, clavatus 

 and furcatus^ having only a single specimen of the latter, and Nord- 

 mann in 1804 added the new species calamus^ which was not figured 

 and has never been seen by any investigator since, but whose descrip- 

 tion and size are sufficient to warrant its validity. 



Claus in 18G8 described in much greater detail Nordmann's type 

 species and the present author did the same for Kr0yer's species 

 furcatus in 190G, still retaining it in the genus and among the 

 Lernaeidae. But after the present detailed study of this family and 

 especially of their internal anatomy the species furcatus can no 

 longer be kept in the genus, and there are many good reasons for 

 transferring it to another family. Chief among these reasons are 

 the following: 



1. While the second and third thorax segments are narrower than 

 the carapace there is no formation of a definite chitinized neck. 



2. The fourth thorax segment is indistinguishnbly fused with the 

 fifth and genital segments, the only indication of its presence being a 

 pair of fourth legs on the ventral surface of the trunk. 



3. The trunk is much too short and too strongly flattened dorso- 

 ventrally for a Lernaean; it has large posterior processes, as long 

 as itself, into which the body cavity extends; it has a distinct abdo- 

 men, also strongly flattened dorso-ventrally, and also with posterior 

 processes into which the body cavity extends. 



4. The second antennae are distinctly ventral and are not chelate, 

 there is no retractile proboscis, and all four pairs of legs are biramose 

 with one-jointed rami. 



5. The ovaries extend forward nearly to the anterior end of the 

 fourth thorax segment; the eggs in the oviducts are more or less 

 spherical and not packed like a row of coins; the QEg strings are very 

 short and stout and there are only 10 or 15 eggs in each string. 



Such cumulative differences necessitate the separation of this 

 species from tlie others in the present genus and the new name 

 Peniculisa furcata is proposed for it. Furthermore, the majority 

 of these differences are just as effective for separating it from the 

 Lernaeidne, and as they all correspond with the characters of the 

 Dichelestiidae the present author would transfer the species to that 

 family. 



This leaves in the genus Pentculus three species already described, 

 to which is here added a fourth that is new to science. 



KEY TO THE SPECIES. 



1. Trunk short, twice as Ion?; ns wide; proboscis also short nnd slender; second 

 antennae enlarged into disks at the tips (u mm.)* calamus Nordniann, 1SC4. 



» Average total length of species. 



