30 Prof. M'Intosh's Notes from the 



their upper part, :i larger neural canal which in some sections 

 exceeds in bulk the main mass of eacli nerve, as in Allen's 

 PcpcilocJueius *. The neuroglia external to the trunks has 

 increased. The condition of tlie dorsal and ventral longi- 

 tudinal nuiscles is the same as in front, the coiled arrangement 

 of the fasciculi being conspicuous in section. 



In a section about half an inch from the tip of the tail, 

 no evident dorsal notch occurs in the hypoderni, but a deep 

 groove exists between the thickened hypoderm on each side 

 of the mid-veutral line. The circular muscular coat is still 

 conspicuous. Each moiety of the dorsal longitudinal 

 muscle is now separate, the outer coil doisally leading ex- 

 ternally to several folds wedged between the moieties, the 

 inner being rounded and smaller than the outer moiety. A 

 strong series of muscular fibres leaves the dorsum, joins the 

 oblique, and passes to the ventral border on the outer side 

 of the nerve-ttuiiks. The arrangement of the coils in the 

 ventral longitudinal muscles in section is as in front, viz., 

 the outer or ventral l)and envelops both moieties which are 

 irregularly rounded and the inner is the smaller. The 

 alimentary canal is small, firm, and rounded, highly vascular, 

 and fixed by the mesenteries as in front, its circular mus- 

 cular coat being conspicuous. The nerve-cords have a 

 considerable mass of neuroglia externally — that is, between 

 tlicm and the cii'cular muscular coat. A small neural canal 

 occurs at the upper and inner border of each, the nerve- 

 tissue completely surrounding it. 



In the Dialychone acustica of Claparede f, the two stato- 

 cysts (otocysts) in the first segment are well developed, but 

 tiie chief interest, in connection with the present remarks, 

 is the characteristically coiled condition of both dorsal and 

 ventral longitudinal muscles (on sec'ion) from the anterior 

 end backward. The large size of the skeletogenons reti- 

 culations and their numerous nuclei are also features of 

 note. In a female large ova occurred in the anterior 

 thoracic region. 



The body-wall in Othonia conforms to the general type 

 of the t:iniily. In those having the body-cavity distended 

 with comparatively large ova the muscular layers are some- 

 what thinner, and the alimentary canal forms an ellipse 

 held by the dorsal and ventral mesenteries, the minute 

 nerve-cords api)arently having no neural canals. 



In Euchone analis (about \ of ati inch) from the front the 



* Jmirn. M. B. A. vol. xlviii. p. 105. 



t Anual. Cli^t. Neap. p. 432, pi. xxx. fig. 3. 



