BY WILLIAM A. HASWELL. 351 



mium on which they are situated. Quatrefages describes Chloraema 

 Dujardinii as possessing a single pair of eyes placed close together. 

 Leuckart describes two pairs of eyes in Siphonostomum vaginiferum, 

 and Johnston* states that Siphonostomum uncinatum possesses 

 four eyes. This is confirmed by Jourdanf as regards S. diplochaitos, 

 and by Joyeux-LaffuieJ as regards Chloraema Dujardinii. I have 

 observed the same to hold good in regard to Siphonostomum ajfine, 

 Stylarioides cinctus, S. Horstii, and Copping eria longisetosa. It 

 seems probable in fact that the presence of four eyes is general in 

 this family. 



The two pairs of eyes in Coppingeria (fig. 26) are situated on a 

 lobe, which is a process from the praistomium between the bases of 

 the branchiae. Into the interior of the oculiferous lobe projects a 

 group of nerve-cells, forming an optic ganglion, which is really a 

 lobe of the brain, with which it is in immediate connection — the 

 optic nerves mentioned by Quatrefages§ not being represented. 

 Both eyes project prominently on the surface, those of the anterior 

 pair being the larger. The cuticle forms a concavo-convex 

 thickening (cu.) over the eye, immediately internal to which is a 

 layer of cells (c), which present no regular arrangement. Then 

 follows a layer of thick crystalline rods (r), which are probably 

 continuous with elements composing a cup-shaped layer of darkly 

 pigmented substance (pi.), outside of which are the nerve-cells. 

 In Siphonostomum ajfine and Stylarioides cinctus the eyes are less 

 prominent, and are buried in the substance of the prsestomial lobe. 



In Siphonostomum affine (fig. 27) they differ slightly from those 

 of Coppingeria. The pigment (pi.) forms an almost complete 

 capsule, with only a small opening. Enclosed within this are a 

 series of thick rods, which fill up the whole of the cavity — there 

 beiug no nucleated elements in the inferior of the pigment capsule. 



* " Catalogue of British Non-Parasitical Worms." 



t " Etude anatomique sur le Siphonostoma diplochaitos, Otto." 'Ann. 



Mus. d'Hist. Nat. Marseille,' Zool. t. 3, Mem. No. 2. This is known to 



me only through the abstract in the "Zool. Jahresb." (1887, Vermes, p. 64). 



X "Sur l'organisation des Chloremiens." ' Compt. Rend.' t. 104, p. 1377. 



§ " Hist. Nat. des Annel6s," tome I., p. 471. 



