DESCRIPTIONS OF GENERA AND SPECIES 217 



on the border-line between segments xi/xii, behind the ventral setae. The structure 

 of the reproductive organs has already been described in treating of the characters of 

 the family. 



(i) Rhynchelmis limosella, Hofpmeistee. 

 R. limosella, Hoffmeistee, Arch. f. Nat. 1843, p. 19a. 

 Euaxes fllirostris, Grube, Arch. f. Nat. 1844, p. 204. 

 Definition. Length, lao mm.; number of segments, 150. Body more or less quadrangular. 

 Prostommm long. Setae posteriorly reduced to one in each bundle ; cAloragogen-covering 

 of gut commences in the seventh segment. Hob. — Euroj}e. 

 Illustrations of this species and of its development are given in the following 

 papers and books: Grube (9, PI. vii. figs, i a-d), Menge (PI. iii. pp. 14-17), 

 KovALEVSKT (Pls. iii-v), Vejdovsky (5, Pis. xxi-xxiv), 24, PI. xii. figs. 33, 34, 

 PI. xiii. figs, i-ii, PL XV. fig. 37, PI. xvi. figs. 1-16). 



(2) Rhynchelmis obtusirostris, Menge. 



Euaxes obtusirostris, Menge, Arch. f. Nat. 1845, p. 31. 



Definition. Length, ^^ mm.; number of segments, 100. Prostomium obtuse. Hal. — 

 Belgium ; Germany. 



The principal reason for retaining this species (figured by Menge [PI. iii. figs. 1-13]) 

 is that d'Udekem and Menge had the opportunity of studying both this species and the 

 last, and were, therefore, presumably not likely to have made an error. Otherwise, 

 as Vaillant says (6, p. 320), the characters are very incomplete. 



Genus Trichodbilus, Clapaeede. 



DEPuriTioiT. Setae simple ; dorsal vessel with 2-5 contractile perigastric branches, 

 but with no caeca ; spermathecae in XI, XII ; male pores on X. 



This genus has been investigated by Clapaeede only. It comes very near to 

 Phreatothrix, from which it differs principally in the fact that it has no caecal 

 appendages of the dorsal blood-vessel. There is but one species — 



Trichodrilus allobrognm, Clapaeede. 

 T. allobrogum, Clapaeede, Mdm. Soc. Phys. Gen. 1862, p. 267. 

 Definition. Length, 25 mm.; about 70 segments. Prostomium 'conical, long, not separated by 

 furrmv from buccal segment. Spermathecae opening behind ventral setae. Nephridia in VI 

 and then again from XII onwards. Hah. — River Seine ( Geneva). 

 The anatomical characters are fully illustrated in Ci.apaeede's memoir. 



Ff 



