POLYNOULE. 



271 



conforming to the dorsal type. Scales twelve to thirty-five pairs or more ; segments 

 carrying these devoid of cirri. Segmental organs (nephridia) opening ventrally on a 

 papilla near the bases of the feet; nerve-cords within the granular layer of the epiderm 

 and between the oblique muscles. Dorsal bristles with more or less tapered simple tips ; 

 ventral bristles with simple or bifid hooked tips. Development by trochophores. The 

 general arrangement of the body-wall in this family may best be understood by con- 

 sulting the accompanying figure. 



Fig. 20. 



cli/- ^^ „ dm. 



i^mj.so. 



Section of body-wall of Polynoe scolopendrina, Sav., in the line of a median dorsal papilla (a), about the 

 middle of the body, b, bases of dorsal bristles; b' , bases of ventral bristles; c, ova scattered in the 

 various parts of the perivisceral (ccelomic) space (pv) ; d, intestine; d', portions of intestinal cseca; dm, 

 dorsal longitudinal muscles; Im, band of longitudinal muscular fibres above the nerve-area; om, oblique 

 and nearly vertical muscles; vm, ventral longitudinal muscles; nc, nerve-cords; dv, dorsal vessel with 

 mesenteries at side; v, ventral vessel with mesenteries; vc, ventral cirrus; so, segmental organs 

 (nephridia). The dorsal cirrus is not shown, nor the perivisceral corpuscles. The drawing was made 

 by Dr. Masterman from a somewhat contracted example. 



Many authors, such as Audouin and Milne Edwards, Johnston, (Erstecl, Grube, 

 De Quatrefages, and Marenzeller, following Savigny, regarded the Polynoidae as one or 

 more genera of the family Aphroclitidae. 



Kinberg, on the other hand, gave them the position of an independent family, or 

 indeed two, if we include Iphione, with the characters indicated in the subsequent 

 summary. In this he was followed by Malmgren and Theel. Olaparede, again, varied the 

 latter arrangement a little by making them his second Tribe, an equivalent position. 



Savigny (1820) placed the Polynoidae as a genus of his family Aphroditae under the 

 Nereids, the general characters being the oval or oblong body, with its elytra, which 

 were typically a dozen pairs, branchiae (which he says are easily recognised), head and 

 its median unpaired, and external antennae, four eyes, and armed papillose proboscis. 

 With the exception of the remarks on the branchiae his description is fairly good. 



By Audouin and Milne Edwards (1834) the Polynoidae were distinguished from the 

 Aphroditidae by the number of their antennae, by the armature of the proboscis, aud by the 

 alternation of scales with cirri. Some have large scales completely covering the dorsum, 

 others have them so minute as to leave the dorsum more or less bare, and in some cases 

 they are vesiculate. The antennae are five or rarely four; proboscis armed with large 

 jaws. The simple branchiae occur with the cirri. The first pair of feet terminate in long 

 tentacular cirri ; the appendages of the last segment form styles. They frequent banks 



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