OLIGOCHAETA BAYLIS. 15 



Enchytroeus carcinophilus, sp. n. 

 Diagnosis : - 



Lt'ntjth, 30-40 nun. Xunilx r of .*<;// /// '///.-, ll!f. <'li<rt<r, :',/>,/ Inunll,' in front of 



; L ( or :! / / Iminll, /x'liiiul it. Jiniin in'iirl;/ xtrni</lit Ix/iiinl, Xc/iliriil in iritli 



funnel only in front <;/' ><'/<////. Spermatkecce tulntlnr, n-itl/ intllx expanded and folded 

 at nlnint tin' in!t/<l/t', inn/ it t'f/r I//HIH/-I;'//* n>'iir tin' external o/,,nin</. Sperm-ducts rrr// 

 long and i'ni/i i/. 



Hah. Stat. 36, South Trinidad Island, S. Atlantic. Living in the interim' of the 

 gill-chambers of a land-crab (<}i-<-ni'fhtiix lagostoma, II. Milne-Edwards). 



III. ANATOMICAL. 



Enchytrceus carcinophilus, sp. n. 

 EXTERNAL FEATURES. 



The largest specimens measure 30-34 mm. in length, and have a thickness of 

 about 0'6 mm. (In the region of the clitellum the thickness is somewhat greater.) 

 These measurements are taken from specimens fully extended, found in a crab 

 preserved in spirit. 



The number of segments, in a large specimen, is about 125. 



The preserved specimens are colourless or slightly yellow. 



The chaetae are short, simple and pointed ; straight, or only to a very slight 

 degree sigmoid. They are arranged in four bundles, or transversely-placed groups, 

 in each segment. In a mature specimen both dorsal and ventral bundles, anterior 

 to the clitellar region, contain three bristles each. Behind the clitellum each bundle 

 (dorsal as well as ventral) contains two or three bristles. In very young specimens, 

 only the first six dorsal bundles contain the full number of three bristles, while in 

 somewhat older individuals, which have as yet no clitellum or genital organs, the 

 first ten bundles were found to lie complete. The first segment (peristomium) is 

 devoid of bristles, as are also the segments occupied by the clitellum. 



There is a minute " head-pore " in, or immediately behind, the groove which 

 marks off the prostomium from the peristomium on the dorsal side. A series of 

 dorsal pores, however, seems to be absent. 



The clitellum. in mature specimens, is a band of thickened epithelium, consisting 

 of a single layer of tall gland-cells, and occupying segments XI.-XIII. At about 

 the middle of its length, on the ventral side, and projecting laterally, are two large 

 spermiducal pores, with thick. Meshy lips (Fig. 8, $). These are exceedingly 

 prominent, and conspicuous to the naked eye. Thev are situated in segment XII. 



The oviducal pores are situated shortly behind the male pores, at the septum 

 between segments XII. and XIII. (Fig. 8, ?). The openings of the spermathecre, of 



