1905.] NATURAL SCIENCES OF PHILADELPHIA. 389 



stones in Casco Bay, ]\Iaine. Here it occurs nearly up to high-water 

 mark in association with Clitellio arenarius, though the latter is far 

 more abundant. In similar situations in Narragansett Bay also both 

 species occur, and Prof. "S^errill has taken them near New Haven. The 

 writer has found T. benedeni only sparingly in the neighborhood of 

 Wood's Hole, and in water both fully salt and brackish. My brother, 

 Dr. H. F. Moore, has collected it along with Clitellio arenarius at 

 Campobello, New Brunswick. 

 Tubifex hamatus sp. nov. PI. XXXII, figs. 12-18. 



Length up to 35 or 40 mm.; greatest diameter about .8 mm. at the 

 genital region; number of somites 85-110. In preserved specimens 

 the prostomium is short and bluntly rounded, the peristomium about 

 as long as the prostomium and divided into two rings, the first of which 

 is papillated and evidently retractile. Succeeding somites increase in 

 size, and the next five or six are biannulate, with the smaller annulus 

 anterior. No further annulation is evident. The greatest diameter 

 is at XI, behind which the segments become much narrower, but under- 

 go no diminution in length for half the length of the body. Many of 

 the specimens have somite VIII and often part of IX or even X strongly 

 wrinkled or furrowed transversely. None has the clitellum distinctly 

 developed. The cuticle is thick and everyT\^here perfectly smooth. 



Setae are absent from the peristomium, the ventral bundle of XI and 

 the anal somite. Elsewhere from one to four occur in each bundle. 

 Anterior to the clitellum four is the normal number both dorsally and 

 ventrally on somites V to VIII, and usually two or three on the remain- 

 ing somites. Postclitellar somites bear almost invariably two in the 

 ventral and a single large one in the dorsal bundles. In no case have 

 capillary setae been detected in the dorsal bundles, the seise being, there- 

 fore, exclusively of the hooked and bifid type. It is, of course, possible 

 that further acquaintance with the species, now known from but one 

 locality, may disclose the occasional or periodical presence of capillary 

 setae in the dorsal bundle. The anterior setae (fig. 14) exliibit no 

 noteworthy peculiarities, and are but little larger in the dorsal than 

 in the ventral bundles. They are slightly sigmoid, with a small 

 nodulus at the junction of the inner and outer limbs, the distal'process 

 of the slightly hooked tip longer and more slender and the proximal 

 one shorter and stouter. Behind the clitellum they undergo little 

 change for several segments, but at about the 20th to 28th somite 

 in different individuals the dorsal and ventral setae become strongly 

 differentiated. The latter (fig. 13) gradually diminish in size and the 

 two divisions of the tip become equal in length, the proximal one, how- 



