706 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxv. 



by H. M. Smith. From Blenny (sp.), No. 6054. From Skate (sp.), 

 No. 12302. From Sculpiu (sp.), No. 12291. From "Bonnet Skate," 

 one lot by Thompson. From Tomcod {Mlcrogadus toincod Walbaum), 

 No. 15446. From Summer Flounder {Paralichthys dentatm L.), one 

 lot by Thompson. 



Color a mottled black, except at the very edge of the carapace, back 

 of the eyes, and around the brain, where it is yellowish; the mottling-s 

 vary much in different individuals in size and extent, and are some- 

 times reddish brown. 



This still continues, as Rathbun stated in 1884, the most al)undant 

 of the genus among the salt-water forms, though megalo2)s is found on 

 a greater variety of hosts. 



(Z(Z^^^=wide, Cauda =tai\). 



ARGULUS MEGALOPS Smith. 



Plate XI; Plate XXVI, fig. 81. 



Argulus megalops SxMith, Invertebrate Animals of Vineyard Sound, Report of 

 U. S. Com. Fish and Fisheries, 1872. — Rathbun, Annotated List of Parasitic 

 Copepods, Proc. U. S. National Museum, VII, 1884. 



Carapace elliptical, longer than broad; antero-lateral sinus narrow 

 and deep, posterior sinus narrow triangular and shallow; abdomen 

 broad elliptical, two-thirds as liroad as long; anal sinus narrow and 

 short; papilhe basal. Sucking disks medium size, situated well for- 

 ward; basal plates on posterior maxillipeds, as well as the maxilli- 

 peds themselves, large and fully armed. The median spines between 

 these posterior maxillipeds are slender and strongly curved. Antenna? 

 rather slender, armed with narrow, sharp spines and hooks. Eyes 

 quite large, their diameter about one-tenth that of the carapace. 



Swimming legs long, projecting some distance beyond the carapace; 

 lobes on the basal joints of the posterior legs in the female with a 

 narrow, conical projection pointing outward. No flagella. 



The peg on the posterior legs of the male takes the shape of a 

 flattened spherical ball with a short, narrowed neck. 



On the side of the peg next the body there is a groove in the anterior 

 surface of the basipod into which the ball can be partially depressed. 

 On the basal joint of the third legs is a stout thumb-shaped projection 

 extending forward from the di,>*tal end of the joint. Smith's three 

 type specimens were females taken at the surface in Vineyard Sound, 

 Massachusetts, July 8, 1871. They were evidently young females, 

 since those since obtained are nmch larger, as will be seen from the 

 measurements here given. This species has a larger number of hosts 

 than any other thus far found, the most common one being the Flatfish 

 {Pseadoplmronectes ainerlcamis Wal))aum). The Museum numbers for 

 this fish are 1322, 1460, and three unnumbered lots from Woods Hole 

 by V. N. Edwards; 8276, 8238 (in part), 12032, 12295, 12296; two 

 unnumbered lots by Thompson, one from Woods Hole and the other 



