[19] OLIGOCHiETOLOGICAL RESEARCHES. 897 



The interior oviduct is of nearly exactly the same form and size a» the 

 penis sheath ; if anything a little shorter. The exterior oviduct does 

 also inclose the penis sheath and interior oviduct securely, and is only 

 sack-like at its lower end, which is rather muscular and unusually short 

 (fig. IIC). The atrium is of somewhat variable form, its upper part 

 sometimes being rather unusually swelled (fig. 11, Cx). More gener- 

 ally the atrium tapers toward both extremities. The receptacle is en- 

 larged at both extremities, the upper one being bent and helix-like (Fig. 

 11^). The testes are found in the tenth to fourteenth or fifteenth setig- 

 erous segments. The spermatophores are numerous, and of variable 

 form (Fig. llefg). 



The segmental organs are comparatively short, surrounded by a heavy 

 mass of granulated matter, but not by any globular cells (Fig. 11/i). 



The length of the body about 25°^™ by 0.75™°^ wide. The integument 

 is very tender, causing the worm to easily break. 



Habitat. — California, Sierra Nevada, in the mud of running springs^ 

 at an altitude of 7,000 feet. 



The principal characteristic of the species is the length and form of 

 the penis sheath and oviducts, also the form of the cephalic ganglion. 



LiMNODEILTJS SiLVANI n. sp. 

 (PI. XIII, Fig. 12; PI. XIV, Fig. 12.) 



Nervous system. — The form of the cephalic ganglion is variable. In 

 large specimens the ganglion is much wider than long, and sometimes 

 furnished with three posterior lobes; in smaller specimens the ganglion 

 is much longer than broad and never three-lobed (Figs. l'2e and 11?/). 

 Between these two forms intermediate ones are found but rarely. 



Generative system. — The lower end of the penis proper is rounded and 

 somewhat swelled. The penis is only half as long as its chitinous sheath 

 and only slightly thicker than the lower end of the atrium (Figs. 122? 

 and 12q). 



The penis sheath is seen from the side gradually tapering towards 

 the exterior apex, with the exception of an abrupt enlargement at the 

 middle, just at the end of the penis proper. Seen from the front, how. 

 ever, it presents a very different appearance. It then nearest resembles 

 an arrow-head or trowel (Fig. 12^, p. s.). 



The oviduct is double. The interior one is about three-fourths as 

 long as the penis sheath. Seen from the side, it resembles an arrow 

 quiver. Seen from the front, its lower end is found to closely inclose 

 the lower, or an arrow-head resembling part of the penis sheath, but its 

 upper third is wider than the upper half of the penis sheath. The ex- 

 terior oviduct is more sack-like, and somewkat loosely incloses the 

 interior generic organs. The efferent duct is extremely long; the pros- 

 tate is very irregular, but rather compact. 



The receptacle consists of three parts, viz : One middle part, which 

 H. Mis. 67 57 



