106 MR. H. CHARLTON BASTIAN'S MONOGRAPH 



permanent tooth. It is not the whole of the rigid spear, however, that is renewed in 

 this manner, but only what appears to he the anterior half of it. 



1. D. STAGNALis, Dujardin. (Plate IX. figs. 35-37.) 

 Dujardin, Hist, des Helminthes, p. 231, pi. iii. fig. C. 



Female. Length -j", breadth xit"' 



External Characters. — Body dark-coloured, tapering gradually anteriorly, but more 

 abruptly posteriorly, where it terminates in a pointed filiform extremity. Head truncate ; 

 no papillae. Integument thick, with longitudinal markings 2-^0^" apart ; lateral pores 

 easily recognizable, and about T^rar" apart. 



Spear -^j^" long. (Esojihagiis ^^th of total length, posterior half enlarged. Intestinal 

 cells having a tessellated arrangement, and containing dark-olive-coloured fat-particles. 

 Posterior portion of intestine for about 5^5" narrower, and very scantily covered with 

 cells and granules. Anus -7V' from posterior extremity. Vulva slightly anterior to 

 middle of body. Oca lying two or three abreast, within uterus. 



Male. Length |", breadth y^". 



(Esophagus proportionally longer than in the female. Anus -^^" from posterior ex- 

 tremity. Sjncides solitary, -^l-o" long. Oblique integumental stria; well-marked. 



Sal). Mud from freshwater ponds, Palmouth ; and New Cross, Kent. 



Individuals of this species were found by Dujardin iu the stomachs of the Carp 

 {^Cyprinus carino) and of Gasterosteus IcBois; which specimens, he conjectures, had been 

 swallowed accidentally by these voracious fish. 



2. D. Cakteri', n. sp. (Plate IX. figs. 38-40.) 

 Female. Length -^^' , breadth 2^". 



External Characters. — Body tapering towards either extremity, especially posteriorly, 

 where it is acu.minated. Head truncate ; no papUlse. Integument thick. 



Sj^ear ^q" long. QiJsojyhagus about |th of total length. Sepiatic or intestinal cells 

 well marked. Anus 43-5" from posterior extremity. Vulva in the middle of body. 

 Ova large. 



Male, same size as female. 



(Esophagus longer. Spicules tto" lo^^o ^^y Woo" broad. Oblique markings of integu- 

 ment for some distance above spicules ; also 8-11 minute suckers communicating with 

 corresponding slanting channels through the integument, about yiVs" apart, in the mid- 

 ventral region. 



E:ab. Stagnant water, with decaying liverwort and moss : Falmouth. 



3. D. OBTTJSiCAUDATTJS, n. sp. (Plate IX. figs. 11, 12.) 



Female. Length ^", breadth xra:"- 



External Characters. — Body tapering considerably for some distance from anterior 

 extremity, but not at aU posteriorly, where it is blunt and rounded. Head truncate, 



I Named after Mr. Carter, so as to connect his name with a species of that genus many of the details of whose 

 anatomy were first carefully recorded by himself. 



