580 FROCEEDINOi:^ OF THE NATIONAL MUSEUM. 



Behind the cephalothorax is a slender neck, one-third the diame- 

 ter of the cephalothorax and of varying length. This is fully chiti- 

 nized and its surface is in some specimens perfectly smooth, in others 

 raised into knobs irregularly disposed. It is attached to the center 

 of the anterior end of the genital segment. At the point of junc- 

 tion of the cephalothorax and neck in all the specimens above enu- 

 merated are three large spherical processes, two lateral and one dor- 

 sal. The diameter through these processes is three times that of the 

 cephalothorax and nine times that of the neck. Quidor found at this 

 point " four cornes, deux dorsales et deux ventrales, dirigees oblique- 

 ment vers I'arriere, de haut en bas et longues de 3 mm." (p. xliii). 

 But as this is the only difference betv.een his specimens and the pres- 

 ent ones, it does not seem sufficient to constitute a separate species. 

 The processes are smooth, vrith a thick chitinous skin and evidently 

 serve the same purpose as the short horns that Quidor found, namely, 

 the anchoring of the parasite to its host. 



The dorsal and ventral surfaces of the genital segment show pits 

 or depressions on either side between the midline and the lateral mar- 

 gin. These pits are of various sizes, numbers, and arrangement, 

 but are most usually four in number, two anterior and two posterior, 

 shaped like parenthesis marks. They are undoubtedly the "deep 

 depressions, funnel-shaped and semilunar " noted by Cornalia at the 

 posterior end of the genital segment, and which he found to be 

 connected on the inside with a strong muscle band. He did not notice 

 or did not mention the anterior ones. But his explanation of them as 

 sucking disks for prehensile purposes is plainly erroneous. The 

 Riuscles are like those in Sphyrion, only here they are gathered in 

 bundles instead of being scattered promiscuously, and the pits on the 

 dorsal and ventral surfaces correspond to the ends of the muscle 

 bundles. When placed in preservatives the muscles usually contract, 

 producing the pits, but they sometimes remain relaxed and then the 

 surface of the genital segment is smooth, although the attachment of 

 the muscles can still be seen through the skin. 



The genital processes at the posterior end of the segment are on a 

 level with the ventral surface, and each is double, consisting of a dor- 

 sal and ventral portion, between which is the opening of the oviduct. 

 The two portions are not in line and so appear double whatever the 

 point of Adew\ From the ventral portion projects a small knob, 

 at whose tip is the opening of the duct leading to the sperm re- 

 ceptacle. 



The egg strings are comparatively very large, as long as the entire 

 body and one-third as wide as the genital segment ; they taper toward 

 the tip, which is bluntly rounded. The eggs are minute ; they are not 

 arranged in regular rows, but there are between 75 and 100 in a cross 

 section of each string, while lengthwise there are from 225 to 250. 



