NO 1302. AMERICAN PARASITIC ARGULID-^^WILSON. 697 



it reaches the posterior border of the thorax, where it turns downward 

 and inward, meeting the corresponding duct from the other side on 

 the midventral line and fusing- in a very short, common ejaculatory 

 duct {e. d.) which opens at the base of the sinus, between the lobes of 

 the posterioi- legs, thus corresponding exactly to the opening of the 

 oviduct in the female. Connected with the vasa deferentia on either 

 side, just where they turn down to meet each other, is a pair of acces- 

 sory blind capsules (Jj. c). These are long and slender, and reach 

 forward far beyond the seminal vesicle and are somewhat enlarged at 

 their anterior ends so as to be club-shaped. All the ducts and the 

 seminal vesicle exhibit peristaltic movements. 



The accessory sexual organs of the male are used chiefly for copula- 

 tion. They are situated upon the two or three posterior pairs of legs 

 and vary greatlv in the various species. 



They are of two kinds, which may be called generic and speciHc. 

 The generic parts, those which are present in all species without 

 much modification, are a peg or blunt spine on the anterior surface 

 of the distal end of the ))asipod of the posterior legs, and a semen 

 capsule on the posterior surface of the legs next in front. The peg 

 and the capsule face each other and are evidently supplementary in 

 function. 



So far as can be determined from preserved specimens, there are two 

 general types of peg in the American species. 



In one, represented hj funduli^ megcdoj^s, alosx, etc., the protuber- 

 ance takes the shape of a spherical ball arising at the base of the exo- 

 pod, but no tubercles can be seen on its surface corresponding to those 

 found m foliaceus (Claus). 



The ball is somewhat flattened dorso-ventrally and is supported on 

 a short narrowed neck. Along the anterior surface of the basipod 

 between the ball and the body is a groove formed by the raising of 

 the edges of the basipod joints. 



The ball can be elevated or partially depressed into this groove at 

 pleasure. The ventral edge of the groove is not even, but is raised 

 into a small flattened plate opposite the base of the ball and into another 

 nmch larger one nearer the body. 



These projections and a part of the ventral surface of the ])asipod 

 itself are roughened ])y chitinous papillary elevations of the cuticle 

 (Plates XI, XII, and XIV). 



The other t3"pe of peg is present in versicolor, lepidmtei, americanus^ 

 etc., and more closely resembles that described iov foliaceus. It con- 

 sists of a blunt papilla at the base of the exopod, ver}^ similar in form 

 to that pictured by Claus for foliaceus and also covered with rough 

 tubercles. 



But from the center of the papilla there arises a long curved spine 

 conical in shape and slightly enlarged at the very tip. 



