NO. 1 HARTMAN: POLYCHAETOUS ANNELIDS 171 



brackets above would include it, since Arabella has dentate forceps 

 (maxillae I), has typically 4 eyes and lacks branchiae. Lais Kinberg, the 

 type of the family Laidea, was later shown to be preoccupied and replaced 

 by Notopstlus Ehlers (1868, p. 406) ; this author added nothing to the 

 original account nor consulted the type materials. Unfortunately, the 

 genus Lais is known only through a single species, L. acuta Kinberg, 

 which is incompletely known. Ehlers thought Notopsilus nearly related 

 to Notocirriis Schmarda (p. 174) ; it may be even nearer to, if not identi- 

 cal with, Arabella Grube, since it lacks projecting acicula and has similar 

 maxillary parts. Kinberg's specimens include 4 anterior ends ; they origi- 

 nated from the La Plata region, Argentina, and are novi^ deposited in the 

 Swedish State Museum. The prostomium is long, depressed conical, 

 nearly as long as the first 4 rings. The maxillary apparatus lies in setigers 

 2 to 6; the carriers are long, slender, extend through 3 rings. Setae are 

 entirely simple, geniculate, pointed, the flange being smooth in some, 

 dentate in others; parapodia have no heavy projecting acicula. 



The Arabellidae are here believed to include the following genera. 



1. Arabella Grube (1850), p. 172. 



This includes both Notocirrus and Aracoda Schmarda, in part, 

 also Maclovia Grube, and questionably Lais Kinberg with its 

 synonym Notopsilus Ehlers. 



2. Biborin Chamberlin (1919) with a single species, B. ecbola 

 Chamberlin. 



3. Drilonereis Claparede (1870), p. 177. 



4. Labidognathus Caullery (1914), p. 180. 



5. Notocirrus Schmarda (1861), Ehlers revised, p. 174. 



Key to Genera of Arabellidae 

 1. Parapodia provided with heavy, projecting acicula (pi. 13, fig. 

 289) 2 



1. Parapodia without such projecting acicula 3 



2. Maxillae I strongly falcate, with (pi. 13, fig. 299) or without 

 teeth at the base Drilonereis, p. 1 77 



2. Maxillae I dentate throughout entire length (pi. 13, fig. 286) 

 or only slightly falcate distally .... Notocirrus, ^. 11 A 



3. Maxillae absent Biborin Chamberlin 



3. Maxillae well developed 4 



4. Free living ; maxillae I strongly dentate ; other maxillary pieces 

 with numerous teeth Arabella, p. 172 



