OBSERVATIONS ON ORIODRILUS LACDUM. 553 



anteriorly), gradually narrowing posteriorly, and ending in 

 a pointed, yellowish, and often regenerated tail. When the 

 worm is contracted the dorsal surface is usually depressed. 



The number of somites is 200 — 250, or more. The somites 

 are well defined, obscurely triannulated, and somewhat pressed 

 together towards the tail. There is no dorsal pore. The last 

 or anal somite is longer than those just in front. The anus 

 itself is dorsal. There are rounded swellings on the somites 

 X, XI, XII, and xiii. 



The prostomium is moderately elongate and as long as the 

 buccal somite, from which it is distinctly separated, without 

 having a prolongation dorsally or a furrow ventrally (HoflF- 

 meister's description — '' Die Lippe ist mit dem Mundseg- 

 ment verwachsen^' — is incorrect). The prostomial pore is 

 indistinct. 



The four rows of setse extend along the corners of the body. 

 The distance between the rows is nearly equal. The setse of 

 each pair are somewhat apart ; they are not prominent, and 

 are slightly curved with rough ends. 



The genital organs are on the same plan as in the Lum- 

 bricinse, and present no peculiarities. The seminal reservoirs, 

 with their lateral cseca, extend through the somites ix to xii. 

 The true testes last for only a short period, during which 

 they early break up into spermatogonia, so that I could recog- 

 nise the two pairs, which lie in the somites xi and xii, only by 

 the remnants. The two pairs of ciliated rosettes have an 

 obscure plate-like structure ; those of the first pair lie on the 

 septum between the somites x and xi ; those of the hinder pair 

 on that between xi and xii, so that they project into the somites 

 XI and XII respectively. The sperm ducts are spirally coiled 

 at the base of the rosettes, unite with one another at the level 

 of the somites xii and xiii, and thence a wider, tortuous, 

 common canal extends on each side to the external pore on the 

 ventral surface of somite xv, between the two couples of setse. 

 The termination is simple ; without an atrium there is only a 

 large gland ("vulva" of Hoffmeister), which probably serves 

 for the construction of the cocoon. There are two pairs of 



