no. 1404. PARASITIC COPEPODS—CALIGIDM— WILSON. 609 



CALIGODES MEGACEPHALUS, new species. 

 Plate XVI. 



Female. — Carapace orbicular, a little longer than wide nearly one- 

 fourth the entire length. Frontal plates distinct and furnished with 

 small lunules, which are better developed than those on Echetus. 

 Frontal margin deeply incised at the center, with the remains of the 

 basal portion of an attachment filament still left in the incision. In 

 this genus, therefore, the development is similar to that of Caligus, 

 and the larva at one period is attached by means of a frontal filament. 



Posterior sinuses small, narrow, and inclined toward the central 

 axis; median lobe but little more than one-third of the entire width, 

 projecting half its length back of the lateral lobes. The latter are 

 rather pointed and curved inward at the tips. Thoracic area small, 

 half the width and a third of the length of the carapace. Eyes small 

 and situated far forward. Free segment elongate, a little more than 

 half the length and one-third the width of the carapace, contracted 

 where it joins the latter, but widened through the bases of the fourth 

 legs (fig. 187). 



Genital segment also elongate, flask-shaped, produced into a long- 

 neck anteriorly, while at the posterior end it extends backward in a 

 narrow lobe on either side of and nearly as long as the abdomen. On 

 the dorsal surface of this segment there is a broad horseshoe-shaped 

 curve, the toe of the shoe formed by a slight projection just over the 

 anus, while the sides of the shoe extend forward in a curve parallel 

 with the margin of the segment. Abdomen elongate, nearty as long- 

 as the genital segment, onty one-fifth as wide as long, and the same 

 diameter throughout, except at the very tip. It shows no trace of 

 segmentation. The anal papillae are very minute and inclined toward 

 each other. The egg cases are narrow, while the eggs are thick and 

 probably not very numerous, although that can not be decided with 

 certainty, since the cases are broken and the posterior portion is 

 lucking. 



Of the ventral appendages the anterior antenna? are as long as the 

 frontal plates, the terminal joint longer than the basal, and both armed 

 with seta 1 in the usual manner. 



Posterior antennae with a short basal joint and a long terminal claw 

 bent into a sickle shape. There is a short and blunt accessory spine 

 at the base of the first joint. 



The first maxilla 1 arc 1 little more than a swelling on the ventral sur- 

 face of the carapace. The second maxilla? are broad and triangular, 

 and as long as the mouth tube. They are removed some little distance 

 from this tube on either side and are rather blunt at the tip. 



The first maxillipeds are short and stout, the joints approximately 

 even, the terminal claws short. The second maxillipeds are large and 



