324 Miscellaneous. 



MISCELLANEOUS. 



On the Affinities of the Genus Polygordius ivith the Annelids of the 

 Family Opheliid.se. By M. A. Giard. 



The Polygordian which I have particularly studied occurs at the 

 point of Eeg-Mell, near Concarnoau, where I discovered it during the 

 spriDg-tides of April. It lives in a coarse shell-sand, like that 

 which covers the tubes of Terebella conchilega. P>y sifting this sand 

 through the fingers one may collect a great number of the Puly- 

 gorclii in a few minutes. The species, which I believe to be new, 

 belongs to the same group as Polygordius lacteus, Schneider, and P. 

 Villoti, Perrier — a group characterized by diceciousness, the length 

 of the body, the circle of anal glands, &c. 



Several months before Perrier, M'Intosh had described, under the 

 name of Limnotrypane apogon, an Annelid which he has sinco 

 thought he could identify with P. Villoti. It is quite certain that 

 Limnotrypane is a Polygordian ; and as it seems to me necessary to 

 divide up the genus Polygordius, I propose, in order to avoid com- 

 plicating the nomenclature, to apply the name Limnotrypane to the 

 dioecious Polygordians, retaining the name of Polygordius for the 

 hermaphrodite species of small size and of more archaic characters. 



The genus Polygordius thus restricted includes the species 

 P. purpureas, Schneider (Heligoland and Sebastopol), and P. flavo- 

 capitatus, Uljanin (Sebastopol). 



The genus Limnotrypane includes L. lactea, Schneider (Heligo- 

 land), L. apogon, M'Intosh (Shetland), L. Villoti, Perrier (Eoscoff), 

 and L. erythrophthalma, sp. n. (Concarneau). L. erythrophthalma 

 is the Polygordian that I have investigated. It may attain a 

 length of more than 0*1 metre. It is of a very bright rose-colour 

 with iridescent reflections. It much resembles L. Villoti and L. 

 apogon, but is distinguished at once from both these species by its 

 red ocular points. L. Villoti is blind ; and L. apogon has the eyes 

 pigmented with black. Further the blood of our species is green, 

 which is not the case in any other known Polygordian. 



At the anterior part of the body the metameres are separated by 

 a very fine black streak ; at the posterior part they are indistinct 

 externally, and marked only by the dissepiments and the enlarge- 

 ments of the digestive tube when the animal is examined by trans- 

 mitted light. 



The cuticle is very thick ; and there are no annular muscular 

 fibres beneath the matrix layer. Nor have I found any annular 

 muscles in the interior of the longitudinal layer. Like Rajevsky 

 I regard the inner lining of this layer as a tissue of connective 

 nature, containing on each side of the general cavity numerous 

 endothelial cells and forming a mesentery above and below the 

 intestine. The vascular apparatus consists of a dorsal and a ventral 

 vessel, united in each metamere by lateral loops, upon which the 

 generative products are developed. The nervous system is formed 

 of two supraoesophageal plates, of a collar, and of a ventral chain 

 placed immediately beneath the epidermis and very easily studied 

 in transverse sections. The segmental organs are straight and 

 ciliated throughout. L. erythrophthalma contains mature ova and 

 perfectly active sperinatozoids as early as the end of April. 



