4i6 WHITMAN. [Vol. IV. 



size from that of the larger metameric spots to much smaller 

 dimensions. All these spots, the metameric as well as the non- 

 metameric, mark low, rounded protuberances. The lateral sense- 

 organs (/) are not placed at the summit of these protuberances, 

 but close to the base, on the outer side. 



On the disc we find yellow patches arranged in about six 

 radial lines, in each of which are seen from two to three sense- 

 organs. These radial rows of sense-organs correspond to the 

 median (w), lateral (/), and outer lateral {pi) rows of the body. 



The ventral surface is paler ; the marginal dark border and 

 yellow V- or u-shaped spots are the same as above, only paler. 

 There are thirteen light longitudinal streaks alternating with 

 dark streaks (twelve in number) (Fig. 2). 



On the ventral side I find six rows of sense-organs, differing 

 from those of the dorsal side only in being smaller and more 

 difficult to find. In all, then, we have fourteen rows of these 

 sense-organs, as in Hirudo. 



The nepJiridial pores {nph.) lie in the first ring of the somite, 

 just in front of the line dividing the ring into an anterior and a 

 posterior half. They are ranged along the medial edge of a 

 broad, light streak, on the outer edge of which are seen the 

 lateral sense-organs. 



The stomach has seven pairs of much-branched diverticula; 

 the seventh diverticulum has five lateral caeca. 



The sexual organs have been figured and described in con- 

 nection with the subject of spermatophores (PI. XIV, Fig. 5). 

 In the same place I have figured the entire central 

 nerve-system, and given two enlarged views of the supra- 

 and infra-oesophageal ganglia (Figs. 6 and 7). 



The number of segments represented in the infra- 

 oesophageal ganglia is five, as shown by the number of 

 nerves, and by the presence of ten median ventral gan- 

 glia (1-5, Fig. 7). The arrangement of these ventral 

 ganglia, shown in the accompanying figure, may be of 

 some value in identifying the species. 



Fig. I. — Ventral ganglia of the infra-pharyngeal portion of the central nervous 

 system, showing that five metameres are represented in this region. 



