178 Prof. M^ntosh's Notes from the 



developed. The oblique muscles pass at each side slightly 

 below the nerve-cord to be attached to the basement-mem- 

 brane ; and at least three neural canals are present, the larger 

 lateral having a coagulable fluid internall}', and each runs 

 along the outer border of the nerve-trunk between the pairs 

 of ganglia. The median or dorsal canal, again, appears to 

 have a separate strand in the interganglionic region, and 

 when it reaches the ganglia it splits into two trunks in certain 

 sections. The muscles of the bases of the feet and of the 

 bristles are also strong. The wall of the alimentary canal 

 appears to be of normal thickness. 



The annelids remained very much in the same condition 

 during December, the great majority of those examined being 

 females, so much so that it was at first considered probable 

 that, as authors had stated, a complex sexual condition 

 existed (e. q. alternate development of the reproductive 

 elements) ; but as a few males w^ere still met with and no 

 trace of an intermediate stage occurred, such complexity 

 could not be proved. This month the only difference in the 

 sections of the females was the increase in the size of the ova, 

 the abundance of the coeloniic corpuscles (PI. VIII. fig. 1), 

 and the distention of the body-cavity and the bases of the feet, 

 so that the muscles of the wall were stretched. The vascularity 

 of the outer surface of the gut also appeared to be increased. 

 The segmental organs showed no feature of note. In the males 

 the perivisceral cavity and the bases of the feet contained 

 dense masses of translucent granular cells, the large nuclei of 

 which stained deeply with cosine. 



The great increase of the large granular cells (PI. VIII. fig. 3) 

 in the ccelomic cavity in January was a feature of moment, 

 especially in those females in which the ova were small. 

 The enormous masses of these cells distended the bodies of 

 the females and they probably increased by division, each 

 being tilled with spherules. In glancing at the living 

 annelids a pale, or greyish, green hue characterized the 

 posterior region of the body in the females; whilst the 

 anterior segments had their vascularity increased, the dorsal 

 vessel of the foot and its branches especially were distinct. 

 "When the posterior region was punctured, the masses of ova 

 had a pale greenish colour as in the previous months, and 

 were similarly unfertilized. As many have discharged ova, 

 it would appear that fertilization is external as in allied 

 forms. 



The sexes are not always distinguished by colour, both 

 males and females being greenish or dull yellowish, though 

 the males are often paler. No change in eyes, feet, or 



