426 



DR W. CARMICHAEL M'lNTOSH ON THE STRUCTURE OF THE 



characteristic notch between this and the large beak, and numerous curved fangs 

 of smaller size above the latter. The fangs above the larger beak are not simply 

 arranged in a linear manner, but, as it were, form a spined knob, with the points 

 curved obliquely downwards. The ventral surface of the annelid is marked by 

 a central blood-vessel, and in spirit thrown into prominent transverse rugae. In 

 my specimens the posterior part of the body tapered to a blunt tail, terminated 

 by two soft papillae ; but these represented the ordinary processes, and probably 

 the tail was absent. The peritoneal bodies are of a pale-red colour, and, as usual 

 in such animals, very large. Dr Malmgren describes the posterior hooks as 

 bidentate, but does not figure them. If this remark is accurate, then the foregoing 

 differs specifically. 



EXPLANATION OF THE PLATES. 



The following letters have been employed as far as possible in designating similar organs in 



Ommatoplea and allies. 



First region of proboscis. 



Second do. do. 



Third do. do. 



Globule in lateral stylet-sac. 



Stylets in do. 



Duct of lateral stylet-sac. 



Muscular chamber behind the floor of the 

 anterior region of proboscis. 



Floor of anterior chamber of proboscis. 



Muscular setting of granular basal appara- 

 tus. 



Granular basal sac. 



Ejaculatory duct. 



Aperture of ejaculatory duct into chamber s. 



External granular glands. 



Reservoir. 



Glands of reservoir. 



Looping muscular fibres of the walls of re- 

 servoir. 



Longitudinal muscular fibres of the walls of 

 reservoir. 



Duct of communication with the posterior 

 chamber. 



Wall of posterior chamber. 



Muscular ribbons. 



a. 



Proboscis 





A. 



ac. 



Reflection of proboscis in front of 



ganglia. 



B. 



h. 



Epidermis. 





C. 



ah. 



Channel in snout for proboscis. 





C. 



c. 



Cutis. 





13. 



d. 



Circular muscular coat. 





8. 



e. 



Longitudinal muscular coat. 





e. 



/• 



Superior commissure of ganglia. 







.'/• 



Inferior commissure of ganglia. 





n- 



h. 



Superior lobe of ganglion. 





6. 



i. 



Inferior lobe of do. 







J- 



(Esophageal apparatus. 





\. 



/• 



Digestive canal-proper. 





p. 



k. 



General stroma of snout. 





P 



1. 



Cephalic vessel. 





V. 



m. 



Cephalic sac. 





g- 



m. 



Duct of do. 





a. 



n. 



Great lateral nerve-trunk. 





T. 



0. 



Proboscidian sheath. 







P- 



Dorsal blood-vessel. 





TO 



a- 



Anastomotic branch. 







r. 



Lateral blood-vessel. 





<P 



ov. 



Ova in situ. 







v. 



Lateral stylet-sacs. 





X 



z. 



Anus. 





+ 



a. Proboscis. 

 ao. Tube for proboscis in snout 



b. Cephalic fissures. 



c. Ciliated epidermis. 



d. External layer of cutis. 



Letters used to designate similar parts in Borlasia and Cephalothrix. 



d'. Basement-layer. 



d". 



e. 



r 



e. 



Pigment-layer in B. olivacea. 

 External (longitudinal) layer. 

 Circular muscular layer. 

 Inner (longitudinal) muscular layer. 



