46 



total in round numbers only ! He based this conclusion on the 

 fact that some scores of leeches of all ages which he examined 

 from various hosts and localities never showed any other 

 number than 33 pairs of gills. The discovery of the present 

 species with 31 pairs is, therefore, important and interesting, 

 in that it shakes what appeared to be a reasonable certainty 

 in Blanchard's conclusion, stated above. On the ventral 

 surface along the boundary of each annulus runs a projecting 

 flange which appears to unite the pair of branchiae of the 

 annulus. 



Pigment. — The whole of the dorsal surface is freely 

 punctuated with black dots, easily visible under a lens ; less 

 freely is this pigment scattered on the gills and on the 

 respiratory vesicles (text fig. 3). The ventral surface is 



Fig. 3. 



Branchellion australis. — Typical gill of preserved specimen. 

 H. V., respiratory vesicle with pigment spots. 



unpigmented except towards the sides near the gills. There 

 are on the dorsal surface, however, very conspicuous patches 

 where the pigment is absent, giving to the unaided eye the 

 appearance of whitish spots. The disposition of these white 

 spots is very different from that in B. torpedinis, where there 

 are six spots on the first annulus of each abdominal segment. 

 In B. australis the spots are variable in number in different 

 parts of the abdomen, being more numerous halfway along. 

 A typical segment exhibits four large spots < 2 ) on the first 

 annulus, easily visible to the unaided eye, eight small spots 

 on the second annulus, and four spots on the third annulus. 



(2) And in the mid-abdominal region there are sometimes two 

 .smaller subsidiary spots. 



