526 lUinols State Lahordtorii of Natural History. 



1 to 2.3. The organ is of firm consistency and- very mus- 

 cular. In shape it is terete with the closed end slightly 

 enlarged and provided with an ensheathing layer of prostate 

 glands (gj^). The protruded penis is a long filiform organ 

 reaching a length of at least 30 mm., though this condition 

 is not exhibited by any of the Illinois examples. 



The female organs are equally and correspondingly special- 

 ized. A pair of ovaries (or) lie on the 2d pair of testes 

 dorsal to the nerve cord and in the posterior end of XIV. 

 Very short oviducts pass from them to a common meeting 

 place, where they are enveloped by the large glandula albu- 

 ginea (go), from which the common oviduct emerges. This 

 narrow firm-walled tube (adc) leads to a large pyriform 

 ovisac (os), which it joins a short distance from the extremity 

 of the narrow end. The vagina (ra) begins near the large 

 end of the ovisac at the posterior end of somite XVI. It is 

 long, slender, and terete, about 2-3 times the diameter of the 

 common oviduct, of an appearance similar to the latter, and 

 with muscular walls. The coil and whorls into which it is 

 thrown are sufficient to give it, when straightened out, a total 

 length equal to the penis sheath. 



Alimentary Canal. — The lip is separated by a slight circular 

 sulcus and fold from the three jaws. Each of the latter is 

 the anterior termination of a pharyngeal fold which here 

 becomes slightly more prominent and curves peripherally into 

 a little pocket into which the jaw may be retracted, so that 

 the whole tooth-bearing ridge may be concealed. The jaws 

 are low and rounded, not at all compressed on the free edge 

 and very little prominent. They bear a double file of 

 large coarse teeth (PI. XLIL, Fig. 7) arranged in from 

 12 to 16 pairs. The individual denticles have bilobed 

 bases and sharp, slightly hooked, apices, those of each 

 pair meeting in a common ridge above the groove which 

 separates their bases. From each side of the pharyngeal folds, 

 which continue the jaws caudad, somewhat lower folds arise, 

 and in the intervals between these three triad systems addi- 

 tional single or double folds may arise. Thus the pharynx 

 is thrown into from nine to twelve, or even more, longitudinal 



