390 . THE ANNELIDA POLYCHAETA. 



Sometimes occurring between tide-marks and in shallow water, but perhaps 

 most commonly to be secured by dredging, being found down to depths of 700 

 and 800 fms. They burrow in the sand and mud, in which they may penetrate 

 to a depth of one or two feet. The habits in general, at least in the case of the 

 best known form, Scalihregma inflatum, are much like those of the lugworm, or 

 Arenicola. They are limivorous. In the intestine {e.g., of Polyphysia jeffreysi) 

 is found sand and mud, in which occur fragments of Foraminifera, Radiolaria, 

 diatoms, sponge-spicules, crustaceans, and other organisms. Known from the 

 temperate seas of both hemispheres and from the cold waters off northern Eiu-ope. 



In general the members of the family are poorly known as to their detailed 

 anatomy, variations, and development. 



Key to Genera. 



a. Prostomium with anterolateral tentacular processes. 

 b. Parapodia of somites behind the twelfth or fifteenth projecting prominently at right angles 

 to the body, each forming a laminate appendage bearing a dorsal and a ventral cirrus. 



c. Branchiae present on the anterior somites Scalihregma H. Rathke. 



cc. No branchiae present Pseudoscalibregma Ashworth. 



bb. Parapodia not forming laminate appendages; no dorsal cirri; ventral cirri either absent or else 

 present in the posterior region alone and digitiform. 

 c. Stout acicular setae present on the first setigerous somite and sometimes also on the two fol- 

 lowing. 

 d. With pigmented ocular bands; ventral cirri present in the posterior region; acicular setae 



present on the first setigerous somite only Sclerocheilus Grube. 



dd. With no ocular bands; no ventral cirri; acicular setae on the first three setigerous somites. 

 e. First three pairs of parapodia greatly exceeding the others in size, elliptic in outUne, and 

 much more widely separated; with a conspicuous anal tube abruptly much narrower 

 than the body, with marginal papillae, but no anal cirri; acicular setae stout, conspicu- 

 ous Gwasitoa, gen. nov.' 



ee. First three pairs of parapodia not thus strongly differing; with 5 slender anal cirri, no 

 such conspicuous anal tube; acicular setae reduced, more slender. 



Asclerocheilus Ashworth. 

 cc. No stout acicular setae on any of the somites; no cirri; an abruptly narrower, cylindrical anal 



tube Kebuita, gen. nov.^ 



aa. Prostomium with no anterolateral tentacular processes; divided by a median groove with each 

 half simply rounded. 



b. Four (or six) pairs of branchiae present on somites II-V Polyphysia Quatrefages. 



bb. No branchiae present Ldpobranchius Cunningham and Ramage. 



This key represents the classification developed by Ashworth (Quart, 

 journ. micr. sci., 1902, 45, p. 237-309, pi. 13-15) in his excellent study of Scali- 

 hregma and its affinities. 



Synonymy of Genera. 



Eumenia Oersted (1843) is preoccupied in the Lepidoptera (God., 1825) 

 as well as by a phyllodocid genus of Risso. Hence I adopt here Polyphysia 



1 Genotype, Oncoscolex heterochaelus Augener. Gosiute, gwasi, tail, and toa, tube. 

 ^Genotype, Eumenia glabra FiUqts. Gosiute, kc, no, and bui, eye. 





