54 SUMMAEY OF CURRENT RESEARCHES RELATING TO 



Although authors do not agree in their views as to the anterior 

 appendages of the body, it is always possible to distinguish dorsal 

 from ventral tentacular cirri : the latter cannot be taken note of in 

 the formation of generic divisions, inasmuch as they insensibly change 

 in form from below upwards ; on the other hand the anterior dorsal 

 cirri are subulate, and differ sharply in form from those which succeed 

 them. 



The Phyllodoceidae, then, are best divided into two groups, one with 

 five, the other with four antennse; in each group there are forms in which 

 the first three dorsal cirri are subulate, and others in which two only 

 have that form. In the second division is ranked a new genus Nothis, 

 in which the third segment is remarkable for having no dorsal cirrus. 



Anatomy of Polynoina.* — A. G. Bourne has recently studied 

 the anatomy of Polynoe cava Mont., and has succeeded in discovering 

 the nephridia. Ehlers had previously described in a P. pellucida a 

 series of contractile sacs opening externally by several ciliated mouths, 

 both upon the dorsal and ventral side of the parapodium, which he 

 regarded as the segmental organs ; but these are, according to Haswell, 

 in reality intestinal cseca ; the true nephridia open upon the ventral 

 papillas which are developed upon all the segments with the exception 

 of the last and the eight anterior ; these ventral papillae are known 

 by the descriptions of Huxley and Grube, and are figured by many 

 other authors, but they were believed to have some connection with the 

 generative functions, owing to the fact that they were found to be 

 filled with ova or spermatozoa at the time of sexual maturity ; the 

 generative products, however, are never found within the lumen of the 

 nephridium, but only in the section of the body-cavity inclosed in the 

 papilla ; they probably make their way to the exterior by a rupturing 

 here and there of the body- wall. The nephridia are short straight tubes, 

 never convoluted though the wall may be variously folded and plaited ; 

 they open internally by a ciliated rosette ; the lumen is enlarged into 

 a vesicle at the base of the papilla ; there are no muscles developed in 

 the walls. Several other anatomical details are given in the memoir ; 

 the elytra are shown to be connected with the " dorsal surface of the 

 somite proper," and not with the parapodium ; in P. areolata, as in 

 Sigalion, rudiments of notopodial cirri may co-exist with the elytra, 

 thus disproving any homology. No blood enters the elytra, but they 

 contain a nervous network ending in small papillae, which are no doubt 

 tactile. 



Spadella MarionLj — P. Gourret has a further note J on this new 

 Chsetognath, in which he gives some account of its body-cavity and 

 generative apparatus. On each side of the pharynx there is a 

 glandular organ which opens by a short canal to the exterior ; its 

 swollen ventral portion is lined by cylindrical or conical cells, the 

 contents of which are sometimes found to be small polygonal bodies ; 

 anatomically, it is perhaps analogous to the segmental organs found 



* Trans. Linn. Soc— Zool., ii. (1883) pp. 347-56 (3 pis.), 

 t Comptes Kendus, xcvii. (1883) pp. 1017-9. 

 j Cf. this Journal, iii. (1883) p. 843. 



