NO. 1404. PARASITIC COPEPODS—CALIGID.E— WILSON. 609 



CALIGODES MEGACEPHALUS, new species. 

 Plate XVI. 



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

 fourth the entire lengtli. Frontal plates di.stinct and furnished with 

 small lunules, which are better developed than those on Eelietn^. 

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

 basal portion of an attachment tilanient 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 l\y means of a frontal iilament. 



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 ti})s. Thoracic area small, 

 half the width and a third of the length of the carapace. P^yes 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 anteriorl3% 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, nearly as long- 

 as the genital segment, only one-flfth as wide as long, and the same 

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

 segmentation. The anal papilhv are very minute and inclined toward 

 each other. The i^gg 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 l)roken and the posterior portion is 

 lacking. 



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

 frontal plates, the terminal joint longer than the l)asal, and both armed 

 with sette in the usual manner. 



Posterior antenna? with a short basal joint and a long terminal claw 

 l)ent into a sickle shape. There is a short and blunt accessor}^ spine 

 at the base of the tirst joint. 



The first maxilhv are 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 



