1917] Essenberg: Some Species of Aphroditidae 403 



broad lip. There are usuall.y fifteen pairs of elytra, occurring on 

 segments 2, 4, 5, 7, and on all alternate segments to 25 ; then on seg- 

 ments 28 and 32. Beginning with the sixth segment are the fimbriated 

 organs occurring on all eirriferous segments. Over the elj-tra is a 

 thick coat of a felty layer, formed by the tufts of dorsal fibers arising 

 from the notopodia. The parapodia are biramous, each ramus being 

 supported by a strong bristle or aciculum. The neuropodium term- 

 inates in a peculiar, three-step-like fashion. There are no lateral 

 prostomial tentacles. The notocirri are long and occur on all alternate 

 segments ; the neurocirri are short, occurring on all segments. 



The presence of the lateral and of the felt fibers, of ocular 

 hemispheres, of the facial tubercle, of the fimbriated organs, and 

 neiiropodia terminating in the three-step-like fashion, and the absence 

 of the lateral prostomial tentacles distinguish the Aphroditidae from 

 the Polynoidae and from any other family of annelids. The genus 

 Aphrodita differs from the genus Laetmatonice in the sessile eyes, in 

 the simple ventral setae, and in a thicker dorsal felt. In Laetmatonice 

 the eyes are pedunculate, the dorsum is covered with thin felt, or 

 the latter may be absent from the dorsum, and the ventral bristles 

 are semipinnate. 



The differentiation of the species is based partly on the size and 

 the shape of the body. Further characteristics concerned in diag- 

 nosis are: the relative length of the neuropodia; the shape of the 

 prostomium; the shape and the size of the ocular peduncles, and the 

 size of the eyes ; the length of the median tentacle ; the relative length 

 of the palpi; the arrangement of the notosetae; the form and the 

 structure of the setae ; the shape of the fimbriated organs and of the 

 elytra ; and, to some extent, the shape and the size of the papillae. 



1 . Aphrodita longipalpa, sp. nov. 



PI. 31, figs. 1-14; pi. 37, figs. 77-78 



Comparison. — The description of this species is based on two 

 specimens which are in the collection of the University of California. 

 They have a slight resemblance to Aphrodita castanea (Moore, 1910). 

 The chief resemblance lies in the arrangement of the dorsal setae, 

 which are recumbent, pointing posteriorly, and covering the dorso- 

 lateral surface of the worm, as in Aphrodita castanea. Probably the 

 latter characteristic led Treadwell to the conclusion that the speei- 



