171] LIFE HISTORY OF GORDIUS AMD PARAGORDIUS—MA Y 51 



sion of the dorsal and lateral lobes. The nerve cord ends at the beginning 

 of the lateral lobes and is partly inturned with the hypoderm that lines 

 the cloaca. On account of this inturning the cord passes into the hypoderm 

 not on the external body surface as it does in Gordius robustus, but in the 

 ventral wall of the cloaca. Here the longitudinal fibers pass into the hypo- 

 derm and to a less extent than in the previous species they also pass around 

 to the dorsal side of the cloaca. 



Peripheral nervous system. Just as in the previous species the peri- 

 pheral nervous system consists of fibers and cells in the hypoderm. Since 

 these structures were clearly described by Montgomery, no detailed 

 account of them will be given here. 



Digestive system. This system is like that found in Gordius robustus, but 

 in the adult condition does open to the exterior at the anterior end. 



Mouth and esophagus. In this species the strand of cells which connects 

 the stylets to the base of the proboscis remains attached to the anterior end 

 of the intestine and is not only retained in the tissue, but actually undergoes 

 development. At first it is a very short connection between the part of the 

 proboscis that does not develop and the anterior end of the intestine, but 

 as development proceeds it elongates and thickens, forming a bulb-like 

 enlargement in front of the intestine with an elongation projecting dorsally 

 over the end of the latter (Figs. 151, 153-4). It passes thru between the 

 dorsal and ventral cell groups of the cephalic ganglion and between the 

 two commissures. In the young stages it has been impossible to demon- 

 strate definitely the presence of a tube in this strand. Altho some sections 

 give the appearance of the presence of a capillary tube, this tube, if present, 

 is so small and its walls so indefinite that it cannot be traced. At about 

 the time the adult cuticula is formed most of the cells composing the strand 

 disintegrate, forming a tube about which the parenchyma cells form fairly 

 definite walls. Some of the outer cells of the strand usually also remain 

 intact and take part in the formation of the walls (Figs. 153-4). By the 

 loss of the proboscis, when the larval cuticula is shed, the tube is opened 

 at its anterior end. 



Intestine. The development of the intestine proceeds in this species much 

 as it does in Gordius robustus. Here also diverticula are formed to receive 

 the oviducts and sperm ducts (Figs. 148, 165). The cells of the intestinal 

 walls are more easily distinguished than they were in the previous species, 

 and an inner, vascular zone is never differentiated. The modifications 

 at the posterior end will be taken up in the discussion of the reproductive 

 system. 



Excretory system. This species also presents no trace of an excretory 

 system 



Circulatory system. No vessels are present, but longitudinal cavities are 

 present in this species as they were in Gordius robustus. Here also the main 



