ZoOL— Vol. II.] RISEN— OLIGOCHMTA. 157 



Habitat. — Santa Rosa Island, and Santa Barbara, Cali- 

 fornia. The writer collected some ten or fifteen specimens 

 in moist garden soil in May and June. I have no hesita- 

 tion in pronouncing this species indigenous to California. 

 Its geographical distribution eastward is probably quite 

 extensive. 



Outwardly this species resembles M. Troyeri, but differs 

 in the size of somite I and in having ventral papillse and a 

 rudimentar}?^ gizzard. It differs from M. Hemfeli\n having 

 the sperm-ducts open into the prostate ; while the deltoid 

 arrangement of the ventral setse is different from that of 

 M. nov(B-zcela7idice. 



Detailed Description. 



Somites. — The somites in front of the clitellum are of 

 about the same size, excepting somite I, which is smaller, 

 its ventral part being only one-half as wide as the dorsal 

 part. Somite X is slightly smaller than somites IX and XI. 



PapillcB.—K pair of papillae surrounds setae a in somite 

 XI, and a single median papilla which, however, is some- 

 times missing, is found in XII. 



Setce. — The deltoid arrangement of the setse is found 

 both anterior and posterior to the male pores. This arrange- 

 ment of the set£e in M. parvus resembles that in M. Troyeri, 

 except that the anterior ventral setse are closer together in 

 the latter species, although not so close as in 3f. Benhami. 

 If we assume that in somite IX the interval between the 

 set« a is equivalent to 11, we get the following ratios: — 

 Somite IX: «-«=ii, a-b^%, b-c^=i^, c-d^=i^. 



Somite XIV: a—a^i^, a-b^^ ; setae c, ^ missing. 



Somite XVIII: a-a^i^ , a—b=^^, b-c=2,S> setce ^ miss- 

 ing. 

 Somite XXV: a-a=^20, a-b^i<,, b-c^i)^, c-d^=i8. 

 Somite XXXIV: a-a=20, a-b^^i"] , b-c=20, c-d=i8. 



The deltoid arrangement begins posteriorly with somite 

 XIII, or thereabout, and ends with somite XVIII. In 

 somite XVIII the distance between setoe a and b is only 



