288 Ww. C. M’INTOSH. 
own drawing show, perhaps fibro-cellular would have 
been a better term to use in describing it. Through this 
investment the radiating muscles in many pass—sweep- 
ing close to the nerve-trunk in its proper sheath, as 
represented in the Ray Society’s work (Pl. XX, fig. 13). 
Now, Dr. Hubrecht in his drawing (Pl. I, fig. 7, op. cit.) 
represents these fibres as ceasing entirely outside the sheath, 
and thereafter as passing only in parallel lines to the cir- 
eumference of the great longitudinal muscles, and the same 
hiatus in regard to the nerve-investment occurs in his 
descriptions. The passage of muscular fibres through 
*“ hemoglobinous nerve-cells” appears to me somewhat in- 
teresting, and in sections they would require special descrip- 
tion. In longitudinal sections the inter-cellular substance 
assumes a more distinctly streaked appearance, and the 
tissue is loaded with granular cells of various sizes, which 
have been first described as nerve-cells by Dr. Hubrecht. 
The whole appears to be attached to the sheath of the nerve 
on the one hand, and abuts on the muscular layer by a 
somewhat better defined margin in transverse sections, the 
muscular fibres formerly alluded to, of course, breaking the 
continuity of the latter. Dr. Hubrecht thus deserves credit 
for the discrimination of this investment as one apparently 
composed of nerve-cells—continuous with the ganglionic 
tissue in front. 
7. Reproductive Organs and Development. 
Dr. Hubrecht observes that “‘ eggs and sperm-sacs (f) take 
their origin between the double interceecal fibrous septa 
(or dissepiments), which separate when the sexual organs 
begin to develop. The characteristic tubes (g, g, Plate XV, 
fig. 3) so distinctly seen in Amphiporus hastatus, as will 
by-and-by be shown, may throw further light on his views 
here, especially as indications of these are observed towards 
the posterior region of the specimen from Naples he kindly 
forwarded to me. 
Lastly, Iam inclined with M. Marion to think that further 
investigation may show some connection between the different 
species of Dr. Hubrecht’s Drepanophorus and M. de Quatre- 
fages’ Amphiporus spectabilis. It is well to bear in mind 
that the latter is characterised by having branched cephalic 
furrows, such as Dr. Hubrecht shows in a diagrammatic 
form in his D. serraticollis. To summarize, therefore, Dr. 
Hubrecht’s results, which he says “ have often confirmed, 
but which have not seldom differed from and contradicted, 
the conclusions and views entertained” by me, we find them 
centre round the following details :— 
