22 CALIFORNIA ACADEMY OF SCIENCES. 
The genera related to Microscolex may be arranged as follows: 
I. Male pore in somite xviii. Nephridia commences posterior to somite xiii. 
PoONTODRILUS and PHOTODRILUS, etc. 
II. Male pore in somite xvii. Nephridia commences in the anterior somites ii to y. 
a, Spermducts open independently of the prostates. RHODODRILUS. 
Sp.: minutus; nove-zelandie. 
b. Spermducts open in the prostate, close to the body-wall. 
1. The set of the inner couples (set 1 and 2) in the vicinity of the clitellum are parallel with 
each other and do not converge toward any one of the genital pores. Nephridia commence 
in ii to iy. MICROSCOLEX. 
Sp.: modestus; algeriensis. 
The sets of the inner couples (set 1 and 2) in the vicinity of the clitellum converge toward 
one or both of the genital pores. Nephridia commence in somite ii to vy. DeLranta. 
Sp.: elegans; Troyeri; Benhami; Poultoni; dubia. 
bo 
DELTANIA. 
Deltania Eisen, Zoe, iv, 250, October, 1893. 
Prostomium encroaches on somite i. Eight setee in four couples ventral and 
lateral, beginning in somite 11. The sets of the inner couples in the genital region 
converging toward the male pore. The sete of the outer couples are further apart 
than those of the inner couples. There are a buccal cavity, pharynx, cesophagus and 
sacculated intestine, but no gizzard, thyphlosole, or cesophageal pouches. Clitel- 
lum, which is perfect, contains three large somites and two outside smaller ones, 
extending from xiii to xvil. No dorsal grooves. Testes in x and xi, free. Sperm-saes 
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. Spermduets open in xvii together with a large prostate which is placed 
parallel to the segmental grooves. The spermducts 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 setee 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 in front of and a little interior to the 4th seta, 
while those posterior to the former open in front of and a little lateral to the 5d seta. 
The nephridia begin generally in ii, rarelyin y. All nephridia furnished with a large 
terminal bladder which in the posterior nephridia develop a ccecal prolongation. 
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 haying a deltoid 
arrangement of the ventral sete 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 sufficiently 
studied, probably on account of the scarcity of specimens for research. 
Among species which must be referred to the genus besides those described 
