190 Transactions. 



detect only ten caeca, of which the anterior two are very small. 

 The crop was partly filled with blood, the four posterior caeca being 

 distended therewith ; the three or four preceding caeca contained 

 more or less blood, but there was none in the anterior caeca. 



The pharynx appears to occupy a greater proportion of the 

 body than usual ; its hinder end reaches to a point at about 

 one-third of the total length of the body, and covers both the 

 median genital organs.* 



I have already, in my previous note, called attention to the 

 edentulous condition of the jaws. 



The genital organs (figs. 11, 12) differ considerably from the 

 typical species — and, indeed, from any other species of Hirudo^ 

 so far as I can ascertain. There are only seven testicular sacs 

 on each side ; the vas deferens is relatively wide as it passes 

 along the series, but anteriorly, in front of the testicular sacs, 

 it becomes narrow, then presents the usual convoluted region^ 

 forming an epididymis or seminal vesicle, whence a narrow 

 muscular " ductus ejaculatorius " passes transversely to a 

 median gland-covered muscular sac of nearly spherical form, 

 which opens directly to the exterior by its ventral surface. 

 There is no narrow " cirrus-sac " such as occurs in other 

 species of Hirudo. The filiform cirrus (which is protruded in 

 one specimen) is contained within this globular sac, which may 

 be termed " atrium." It corresponds to prostate + penis-sac. 



The female organs are also difierent from the type. The 

 ovarian sacs are conspicuously large — larger, indeed, than the 

 " albumen gland," alongside which they lie. The muscular 

 vagina is a short U-shaped tube, which, as it approaches the 

 body- wall below the gland, becomes greatly dilated, so that its 

 diameter is nearly as great as that of the overlying gland. 



Remarks. — It may be necessary to form a new genus for 

 this species, but at present I have not sufficient literature at my 

 disposal to allow me to do so with surety. 



The only other leech, so far as I am aware, in which the 

 number of testes is so small as seven pairs is Pkilobdella, Verrill 

 — which, however, is possessed of characteristic and unique 

 " copulatory glands," opening on to pits which appear to serve 

 as adhesive organs in copulation. Moreover, the genital pores 

 are separated by less than one somite ; the annulations of the 

 body in P. gracile, Moore (12), at any rate, being more complex 

 than in Hirudo. There are also other differences. In Limnatis, 

 however, the number of testes is eight pairs, according to Mocfuin- 



* In H. medicincdis the hinder end of the pharynx is at a point well in 

 front of the genital organs, about one seventh the total length, and in 

 H. mauinna this point is at about one sixth the length. 



