2 Prof. M'Intosh's Notes from the 



Amongst others, R. Wagener* (1832) describes the 

 alimentary canal in Sabella ventilabrum (S. penicillus, L.) as 

 having two sacs in front, such apparently, from his figure, 

 representing the anterior nephridia. He pointed out the 

 commissures connecting the great nerve-cords. 



Milne-Edwards (1838) considered the circulation in the 

 Sabellids to be akin to that of Nephthys and the Nereidse, 

 a dorsal and a ventral trunk being present, and the inner 

 aspect of the integument is supplied with a multitude of 

 vascular filaments for the secretory organs, and, with the bases 

 of the feet, present also a capillary rete which probably aids 

 in respiration, though the main respiratory organs are the 

 cephalic fans. He did not allude to the special vascular 

 sinus around the gut. 



Grube (1838) gave a general account of the structure of 

 Sabella unispira (Spiroyraphis spallamani), especially of the 

 alimentary and circulatory systems. He pointed out that 

 Leuckart was wrong in attributing two vascular trunks to 

 each branchial filament. He thought that the anterior 

 (thoracic) nephridia were connected with reproduction. 



Kollikerf, in his researches (1856), describes the " carti- 

 lage" of several annelids, such as Sabella unispira (Spiro- 

 graphis spallanzani), but he was uncertain as to the distinc- 

 tions between the blood-vessels and the nerves of the 

 filaments, and his figures indicate that his " Knorpelfaden " 

 structurally differs from that described here. He noted the 

 specially thickened hypoderm (his epithelial layer). 



De Quatrefages (1850) thought that in the branchiae of 

 the Sabellidse and Serpulidse are venous and arterial twigs, 

 which mingle in a system of vessels the walls of which 

 cannot be distinguished from the surrounding tissues, and in 

 which respiration is carried on through the thin covering 

 tissues and their cilia. He describes in these branchiae what 

 he terms a cartilaginous skeleton, composed of cells surrounded 

 by a tough fibrous investment like a periosteum. According 

 to this author, the cephalic ganglia in Sabella flabellata, 

 Savigny, form two pairs connected by a large commissure, 

 and from these branches go to the branchiae and the eyes. 

 The oesophageal connectives are very short. The visceral 

 system seems to arise from these ganglia as a small twig on 

 each side furnished with two ganglia. The great ventral 

 nerve-cords are separate throughout, though nearer each 

 other posteriorly, and the first ganglia are close to the cephalic, 



* 'Isis,' 1832, p. 655, Taf. x. 



t ' Untersuchungen z. vergl. Gewebelehre augestelt in Nizza im 

 Herbste ' (1 Sitzung. 13 Deo.)- 



