HESIONIDAE. 183 



which is the same as flavum Oersted, the type of Sphaerodorum which has the 

 priority. 



Ephesia Rathke is preoccupied by Ephesia Hubncr (Lep., 1816). It was 

 incorrectly restricted by Perrier to species with composite setae, since its type, 

 E. gracilis, has simple setae. 



Hesionidae. 



The hesionids are sylloid annelids of but moderate size, in which the number 

 of somites may be as low as twenty-one and only rarely exceeds forty. They 

 are often conspicuously and briUiantly colored and marked, transverse stripes 

 being common. 



The prostomium commonly bears a pair of biarticulate palpi. The ten- 

 tacles may be three, two, or altogether absent. There are two pairs of eyes. 



The first one to four somites following the prostomium may be distinct or 

 they may be more or less completely fused. From the first one to all four of 

 these somites may be achaetous and bear each two pairs of tentacular cirri, which 

 accordingly number two pairs, six pairs or eight pairs, while in Taphus none at 

 all are present. Nuchal organs primitive. 



On all succeeding somites the parapodia are normal and either uniramous 

 or more or less distinctly biramous, as in the most speciaUzed genera of each of 

 the groups into which the family is separable. Dorsal and ventral cirri are 

 present; they are fiUform, frequently very long, and usually more or less dis- 

 tinctly articulated, often moniliform. 



The reduced notopodia, when at all present, bear simple setae, the neuro- 

 podia composite setae. Rarely (Ancistrosyllis) all the setae are simple. The 

 acicula are in most cases characteristically black in color. 



The pygidium bears two anal cirri. 



The proboscis is eversible, strongly developed, and may be wholly smooth, 

 may bear simply a crown of papillae, or may be armed with maxillae or stylets 

 or both. Capable of great distention. 



A pair of elongate caeca, capable of distention with gas, arising between 

 oesophagus and stomach, or sometimes but one distensible division without caeca. 



There is no sharp line of demarcation between the less specialized genera of 

 this family and the Syllidae, as is indicated by such names among hesionids, as 

 now accepted, as Ancistrosyllis and Syllidea. There seems no doubt that under 

 Schmarda's genus Cirrosyllis (Neue wirbellose thiere, 1861, 2, p. 76) are included 



