22 CALIFORNIA ACADEMY OF SCIENCES. 



The genera related to Microscolex may be arranged as follows: 



I. Male pore iu somite xviii. Nephridifi commences jiostei-ioi- to somite xiii. 



PoN'TOURiLus ;iik1 Photodriu's, etc. 



II. Male pore iu somite xvii. Nepliridia commences iu the auterior somites ii to v. 



a. Spermdncts opeu iudepeudeutly of the prostates. RnononRiLus. 



Hp.: minntua; noviv-zelnntUtf . 



b. Spermdncts ojieu in the prostate, close to the body-wall. 



1. The seta? of the iuuer couples (setie 1 and 2) iu the vicinity of the clitellnm are parallel with 

 each other and do not converge toward any one of the genital pores. Nephridia commence 

 iu ii to iv. Mic'Ro.scoLEX. 



Sp.: modesiii-t; ahjcrkitslx. 

 '2. The set:e of the iuuer couples (setro I aud 2) iu the vicinity of the clitellum converge toward 

 oue or both of the genital pores. Nephridia commeuce iu somite ii to v. Delt.\nia. 



Sp.: eler/ans; Troyeri; Benhami; PouUotii; duhla. 



DELTANIA. 



De/tania Eisen, Zoe, iv, 250, October, 1893. 



Prostominm encroaches on somite i. Eight seta? in four couples ventral and 

 lateral, beginning in somite ii. The set-po of the inner couples in the genital region 

 converging toward the male pore. The seta^ of the outer couples are further apart 

 than those of tlie inner couples. There are a buccal cavity, pharynx, oesophagus and 

 sacculated intestine, but no gizzard, thyphlosole, or oesophageal pouches. Clitel- 

 lum, which is perfect, contains three large somites and two outside smaller ones, 

 extending from xiii to xvii. No dorsal grooves. Testes in x and xi, free. Sperm-sacs 

 present, free. Spermatheca present or absent, variable in position and shape. 

 Ovary one pair in xiii. Oviduct one pair in xiv. Two pair of ciliated rosettes in 

 X and xi. Spermdncts open in xvii together with a large pro-state which is placed 

 parallel to the segmental grooves. The spermdncts join the muscular part of the 

 prostate at the point where it enters the body-wall. The glandular part of the prostate 

 consists of two layers of cells. Penial setfe open in the same duct as the prostate. 



The dorsal vessel with three pair of lateral hearts in x, xi and xii. No sub- 

 neural vessel. Only very few blood vessels on the nephridia. 



Nephridia are of two slightly different kinds. Those in the first few anterior 

 somites, commencing in somite ii, open iu front of and a little interior to the 4th seta, 

 wliile those j^ftsterior to the former open in front of and a little lateral to the 3d seta. 

 The nephridia begin generally in ii, rarely in v. All nephridia furnished with a large 

 terminal bladder which in the posterior nephridia develop a coecal prol(jiigation. 



Small, transparent-glassy, more or less colorless worms with orange colored 

 clitellum, and living in moist, especially sandy soil. 



Systematic position. Under the genus Deltania I group all species which 

 would otherwise be referred to Microscolex Rosa, but which agree in liaving a deltoid 

 arrangement of the ventral sette surrounding the generative and especially the male 

 pores. With this character I believe a closer investigation of the species of Microscolex 

 will join others, principally in regard to the nephridia which have not been sufficient!}' 

 studied, probably on account of the scarcity of specimens for research. 



Among species which must be referred to the genus besides those described 



I 



