NEW GENEEA AND SPECIES OF EARTHWORMS. 255 



velopment of the "lymph spaces" found in the muscular 

 layers of all Oligochaeta. 



The setse are, as in the Geoscolicine genera Pontoscolex, 

 Diachseta, and Onychochaeta, disposed irregularly, though 

 there are but eight to each segment. As in Diachseta, there 

 are fourteen rows; as in Diachasta Thomasii, the ventralmost 

 seta on each side of the nerve-cord is repeated from segment to 

 segment without any alteration in its position. There are thus 

 two rows of setse, which are perfectly regular and in line. 

 The form of the setse differs from that of any setse that have 

 been hitherto met with in the Oligochaeta, unless, indeed, 

 the setae of Hypogaeon hirtum are similar. Savigny^ 

 speaks of the setae of that species, which has not been met 

 with again, as being spiny j moreover, Savigny mentions that 

 the clitellum is " entierement recouverte de soies inegales, dis- 

 posees confusement.'' It may be that Hy pogaeon hirtum is 

 a near ally of, if not identical with, the present species. It 

 comes from America, near to Philadelphia. 



In Trichochaeta hesperidum the free extremity of the 

 setse (see fig. 2) is furnished with six or eight short and deli- 

 cate processes, which end in a point directed forwards ; other- 

 wise the shape of the setae conforms to the usual pattern found 

 in earthworms : the extremity is, however, as in the worm 

 Pontoscolex corethrurus, slightly bifid at the extremity; 

 there is a small semicircular notch. The setse at the end of 

 the body are exactly of the same form, and are no larger than 

 elsewhere. 



§ Internal Anatomy. 



The alimentary canal has a large gizzard in Segment 6. 

 There are no calciferous glands. 



Behind the gizzard are several thickened intersegmental 

 septa. There are five of these — the same number as in 

 Diachaeta Thomasii. 



The nephridia are, as in all other Geoscolicidae, paired 



' * Syst^me des Ann^lides, principalement de celles des Cotes de I'^gypte 

 et de la Syrie, &c.,' p. 104. 



