252 AET. II. — A. IZÜKA : 



Key to the Families of Polychaeta Errantia 

 represented in Japan. 



aJ Segments dissimilar. 

 hJ With elytm. 



cJ Dorsal cirri alternate with el3^tra. 

 d.' Jaws horny. 



e.' Elytra not on every alternate segment 



. . Polynoidae, p. 7. 



e." Elytra on every alternate segment .. ^coei/c^ae, p. 65. 



d." Jaws none, or rudimentary . . . . ApJiroditidae, p. 73. 



c." Dorsal cirrus on each parapodium . . Sigalionidae, p. 85. 



h." Without elytra . . Palmy ridae, p. 93. 



a." Segments similar or subsimilar. 



h J Buccal armature complex .. .... .. . .Eimicidae, p. 95, 



h." Buccal armature simple or none, 

 c' . Prostomium of ordinary form. 

 d.' Without branchiae. 



e.' With a pair of jaws, and with paragnathi or 



papillae Lycoridae, -p. 146. 



e." Without jaws and paragnathi. 

 /.' Cirri simple. 



(jj Tentacular cirri 2 or 4 ..Syllidae, p. 181. 

 g." Tentacular cirri numerous Hesionidae, p. 191. 



/." Cirri lamellar PJiyllodocidae, p. 194. 



d." With branchiae. 



eJ Branchiae cirriform Nephthydidae, p. 212. 



e." Bi'anchiae arborescent . . . . A'mpliinomidae, p. 218. 

 c." Prostomium conical and annulated. 



dJ Parai^odia unlike in shape in anterior and xx)sterior 

 regions of body ; x>i'oboscis with numerous dissimilar 



jaws Goniadidae, j). 231. 



d." Parapodia similar in all segments ; proboscis with 



4 similar jaws Glyceridae, ]). 237. 



