174 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 50. 



D E N S I S . 



VIEW OF HEAD OF MALE. 



not far anterior of the tip of the tail. The spicules are unequal, 

 slightly curved, the right one 145 n long and the left one 180 fi 

 long, measured in a straight line from tip to tip. The maximum 

 thickness is 13 to 16 /a. The mouth has the structure characteristic 

 of the genus, but few details are visible in the specimen available. 



Two large and j)rominent teeth, one dorsal 

 and one ventral of the esophageal lumen, are 

 visible in a latero-dorsal view of the head 

 (fig. 226). These teeth are continuous with 

 the other chitinous structures of the mouth 

 capsule and are borne on the chitinous plate 

 which makes up the base of the capsule and 

 is itself a continuation of the walls of the 

 capsule. There is apparently another tooth 

 on each side of the 

 lOrniTI large ventral tooth. 



Fig. 226.— rictularia colora- -^hc mouth aperture 



Latero-dorsal ig sun'OUnded by a 



corona radiata, a 

 small circlet of denticles. Only the ventral 

 head papillae are visible in the available 

 specimen. 



Female, estimated length about 9 to 10 

 mm., based on an incomplete specimen 8.463 

 mm. long with the posterior extremity miss- 

 ing. Maximum thickness 360 /x. Thickness 

 at vulva 270 /x. Head 120 /x in diameter at 

 the base of the buccal capsule. Esophagus 

 1.5 mm. long. Nerve ring 250 ju, from the 

 anterior end of the body. Vulva opposite 

 posterior end of esophagus and therefore 1.5 

 mm. from anterior end of body; between 

 the thirty- first and thirty-second comb (fig. 

 227). The transition from combs to spines is 

 fairly distinct, but by no means abrupt. 

 There are three combs posterior of the vulva, 

 making a total of 34 combs. The post- 

 vulvar combs are of a transitional type, com- 

 bining the length of a comb with the sharp 

 point of a spine. The anterior end of 

 the first comb in the head region extends anterior of the base 

 of the buccal capsule. There are 30 spines of a fairly imiform 

 type following the combs, but as the specimen is incomplete 

 posteriorly this does not represent the total number present in this 

 species. The combs attain a maximum height of about 42 /x. The 



10 mm. 



Fig. 227.— Rictularia colora- 

 DENSis. Anterior extrem- 

 ity of female, v., Vulva. 



