116 ANATOMY OF THE ANOPLA. 



apply to the Enopla, with two exceptions, which represent transverse sections of Cerebratulus 

 marginatus. In that through the anterior part of the body five circular vessels at least are 

 transversely cut in the meshes round the oesophageal region, and, moreover, they are joined 

 by a pink band in the figure, apparently from a connecting trunk. I fear the author has 

 been misled by the carmine used in the preparation, for in the British examples of " Cerebratulus " 

 the arrangement characteristic of the Lineidce is found. 



12. Organs of Reproduction. 



The sexes in the known Lineidee are separate, and the ova and spermatozoa developed in 

 their respective sacs between the inner muscular layer of the body and the digestive cavity. The 

 glandular elements in the walls of the latter, indeed, undergo a certain amount of atrophy during 

 the period of reproductive perfection (Plate XXI, fig. 1). Both ova and spermatozoa escape by 

 pores a little above the lateral nerve-trunks, the apertures being frequently indicated by pale 

 specks (Plate IV, fig. 2). In Carinella annulata they are often boldly marked by white spots 

 (Plate VII, fig. 5). In this species also, as well as in L. gesserensis (Plate XVIII, fig. 11), the 

 rudimentary condition of the generative organs may be seen in transverse section as a series of 

 small globular or pyriform sacs, filled with granules and globules, and situated above the nerve- 

 trunk on each side of the body. 



a. Male Elements, 



In Lineus gesserensis the spermatozoa (Plate XXI, fig. 10) have the aspect of slender rods, 

 with a scarcely perceptible enlargement at the end from which the filiform tail proceeds. When 

 a mass is taken from a living animal, groups often adhere to a point by one end, and, spreading 

 in a radiating manner, lash the surrounding water with their tails. The spermatozoa of 

 L. sanguineus (Plate XXI, fig. 11) are more minute than the former, and somewhat resemble 

 an awl-handle in shape, with the filament projecting from the butt, which is thus frequently 

 agitated, while the tapered end is comparatively still. In Lineus marinus the outline of the body 

 of the spermatozoon (Plate XXI, fig. 12) is less regular than in the foregoing, and seems slightly 

 crenate in some specimens. A very long filament is attached to the larger end. In Micrura 

 fasciolata there is likewise a slight constriction in the middle of the spermatozoon, and the tail 

 proceeds from the larger extremity. The reproductive elements were nearly perfected in the 

 large Zetlandic variety of this form in August, the sperm-cells being filled with slightly curved 

 rod-like bodies, having one end less tapered than the other. 



b. Female Elements. 



The ova occupy similar positions to those of the Enopla. They are few and large in Lineus 

 gesserensis, smaller and more numerous in L. sanguineus. 



