No. 377-]| REVIEWS OF RECENT LITERATURE. 359 
reticulata, sp. nov., Polynoé gigas, sp. nov., Polynoé lordi Baird, Polynoé 
pulchra, sp. nov., Polynoé fragilis Baird; HARMOTHOE Kinberg (Sens. ext.) 
(including Antinoé, Harmothoé, Hermadion, Kinberg; Eucrante, Eunoa, 
Evarne, Lenilla, Lagisca, Melenis, Nychia, Malmgren; /Polyeunoa 
M'Intosh): Harmothoé imbricata (L.) Malmgren, Harmothoé hirsuta, 
sp. nov., Harmothoé crassicirrata, sp. nov.; Sigalionide: PEISIDICE, gen. 
nov., Petsidice aspera, sp. nov., Sthenelais fusca, sp. nov., Sthenelais ver- 
ruculosa, Sp. nov. 
Concerning the classification of the polynoids, the author tells us 
that he has been strongly tempted to follow the more conservative 
students of the group and place the forms he has studied all under 
the type genus Polynoë; but that, after a careful study of the material 
at hand and the literature available, he has become convinced of the 
practicability of arranging nearly all the known species under two 
genera, viz., Polynoé Savigny and Harmothoé Kinberg. He wishes it to 
be fully understood, however, that he regards this as provisional only. 
Collections have been made at numerous points, from San Diego 
on the south to Puget Sound on the north. Most of the species have 
been collected by the author himself, and have been studied in the 
living condition. 
Numerous interesting observations on the habits and variability of 
several of the species are recorded, none of which are more interest- 
ing, perhaps, than those pertaining to the commensalism exhibited 
by some of the species of the genus Polynoé. Thus we are told con- 
cerning P. érevisetosa that “ probably no species of this great family, 
noted for the morphologic plasticity of many of its members, is more 
variable than this. ‘The variation it exhibits is unquestionably due 
to differences in its environment.” Some of the individuals are free 
living, while others are commensal in the tubes of species of Amphi- 
trite and Thelepus. “Like another tube-commensal of our coast, 
Polynoé reticulata, it attains a larger size in this mode of existence 
than when free living, but not unless it lives in a tube of liberal 
dimensions, so that both the rightful occupant and its messmate have 
ample space.” The commensal individuals are said to be proportion- 
ally longer and narrower than the free-living ones, and furthermore 
to exhibit certain structural peculiarities, most of which appear to be 
the direct result of their mode of life. The elytra are thinner and 
smoother, and not so likely to extend to the extreme posterior end of 
the body. And, what is still more significant, the elytra of the ventral 
series tend to develop a strong upper bristle, which the author thinks 
is of advantage in crawling into the tube. A very curious thing in 
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