Ko.lieo. LEECHES OF THE U. S. NATION AL MUSEUM— MOORE. ool 



H^^MENTARIA De Filippi. 



7. HiEMENTARIA OFFICINALIS De Filippi. 



No. 1478, U.S.N.M. Guanajuato, Mexico; Prof. A. Dugcs. Two 

 specimeus. 



1 auiily ICHTHYOBDELLID.E. 



TRACHELOBDELLA Diesing. 



8. TRACHELOBDELLA VIVIDUS. 



(Plate XL, tig. 4. j 



Cifstobranchus ritiduH VKUKlLr,. 



Thi.s species bear.s a striking re.seml>lance to a Cifstobratichns, but the 

 annulation and tbe position of tbe sexual pores are characteristically 

 that recently attributed bN' Blanchard to Trdchdobdella. 



The two regions of the body are sharply di.stiuguished. The anterior, 

 which contains tbe first eleven somites, is somewhat sunken into and 

 embraced by the first somite of tbe posterior region. Somites IX, X, 

 and XI are narrowed to form the clitellura, in front of which tbe body 

 is slightly exx>anded laterally. The anterior region includes twenty 

 distinct primary annuli posterior to the expanded "bead," which latter, 

 with the first five annuli, constitute five somites. Sonjite \'I is com- 

 po.sed of three primary annuli, each of which is clearly biannulate. 

 Somite VII is as large as the eight preceding annuli. Each of the pri- 

 mary annuli is divided into two and these again halved dorsally, so that 

 twelve annuli of the third order may be counted on the dorsal side. 

 The middle ]»rimary annulus {a 2) of this .somite is large, and its two 

 .secondary annuli ih .5 and 4j have almost the value of the adjacent 

 I^rimary annuli. Somite VIII is similarly annulated, but shorter. The 

 somites IX, X, and XI are the clitellar .somites and are each reduced to 

 two primary annuli, which, with the exception of the last, are obscurely 

 biannulate. The male pore is located on tbe anterior margin of somite 

 X, or between this and the preceding annulus (16j. On the ventral 

 side annuli sixteen and seventeen are much enlarged and partly fused 

 with fifteen and eighteen, respectively. The female pore is between the 

 eighteenth and nineteenth annuli, having the same relation to somite 

 XI as tbe male pore has to X. The twentieth annulus is obscure, being 

 united with and retracted within .somite XI. 



Tbe posterior body region is Ijroad and depressed, the transverse and 

 vertical diameters being about as two to one. The con.striction shown 

 in the figure in the posterior third of the body is probably the result of 

 an accident of preservation. The somites of this region are charac- 

 terized by the six secondary annuli, tho.se of the .second primary 

 annulus f« 2j being largest and on tbe dorsal .side again divided into 

 the tertiarj' annuli, thus: /> 1-2 -fc 5-6-7-8-1-/^ 5-0. This latter char- 

 acter is lost in the i>o8terior somites. Somite XXII is the last comxdete 



