18 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.60 



Posteriori}' the walls of the ducts are thickened and serve as glands 

 for the secretion of the cement substance which forms the walls of 

 the spermatophores. In Dichelesthium^ Nemesis^ and Eudactylina 

 the general course of the ducts is the same, but the first long fold is 

 omitted and there are not as many convolutions. 



Inside the spermatophore receptacles the sperms are gathered into 

 the spermatophores, which are afterward attached to the females. 

 These spermatophores are ellipsoidal and in Lernanthropus the ends 

 of the discharging tubes, where they are applied to the vulvae of the 

 female, are swollen into large brown spherical receptacles, which 

 remain in place on the vulvae long after the spermatophore itself 

 has disappeared (fig. 104). In Dichelesthium the spermatophores 

 are narrower ellipsoids and are attached side by side on the midline 

 of the abdomen close to the genital segment. Their discharge tubes 

 then cross each other and enter the vulva on the opposite side. 



Nervcnis system: — The nervous system includes first a supra- and 

 an infra-esophageal ganglion. The former takes more or less the 

 shape of a flattened cone, and from the anterior end nerves are sent 

 to the first and second antennfe and the anterior part of the head. 

 The pair running to the first antennae originate close together at the 

 center of the anterior end of the ganglion in Lernanthropus ; they are 

 apparently fused into a single strand for some distance, then separate 

 and enter the base of each antenna. In Dichelesthium they originate 

 at the corners of the anterior end and are divergent. Outside of this 

 first pair arises another nerve on either side which goes to the second 

 antenna. The infraesophageal ganglion is considerably elongated 

 and tapers gradually backward into the ventral nerve trunk. From 

 it branches extend to the mouth parts, the swimming legs, and the re- 

 productive organs. 



The ventral nerve trunk runs back to the fifth thoracic segment 

 and there divides, the two branches separating a little and continuing 

 through the fifth and genital segments. From the ventral trunk 

 branches are given off to the various muscles of the thorax, and from 

 the two posterior branches of the trunk itself are supplied the nerves 

 leading to the muscles controlling the vulvae and semen receptacle in 

 the female, and the spermatophore receptacles and ejaculatory ducts 

 in the male. They also control the dilator muscles of the rectum 

 during respiration (see fig. 71). 



Vascular system. — Since only a single genus. Lernanthropus^ pos- 

 sesses anything in the way of a vascular system, the description of it 

 is reserved for that genus alone. In other genera circulation is 

 accomplished by means of the peristaltic movements of the digestive 

 canal together with those concerned in rectal breathing. In most 

 genera, however, there is very little movement of the fluid contents 

 of the body cavity. 



