NO. 1175. ISOPODS OF THE PACIFIC COAST— BICHAEDSON. 847 



Habitat. — Puget Sound; Monterey Bay, California, collected by Mr. 

 Heath. 



A specimen from Monterey Bay, California, agrees with Miers's 

 description of two males received from California, which he refers to 

 this species. It is unlike Idotea icosncsenslcii in the following points, 

 and from an examination of a large number of individuals of I. u-osne- 

 senslii, in which these points remain constant, it seems to demonstrate 

 the impossibility of uniting the two species. 



1. "Form of epimera of second to fourth thoracic segments, which 

 reach quite to the posterolateral angles of these segments, 



2. "Epimera of the second segment are broader anteriorly, and the 

 terminal segment more resembles tliat of I. ochotensis, being more 

 angulated and less rounded at the posterolateral angles."' 



3. The absence of hairs on the legs. 



The legs of I. icosnesenslcii (the males) are thickly covered with hairs 

 and very bushy in appearance. 



4. The smooth margins of the epimera, which, in I. tvosnesensJcii have 

 thickened edges. 



19. SYNIDOTEA Harger. 



ANALYTICAL KEY TO THE SPECIES OF SYNIDOTEA.^ 



a. Abdomen emarginate or notched at its distal end. 



b. Two spines or tubercles overhanging the frontal notch. 



c. Spines united near the base 45. Synidotea pallida Benedict. 



c '. Tubercles free at base 46. Synidotea erpsa Benedict. 



b '. No spines or tubercles overhanging frontal notch, 

 c. With a low ridge arising between the eyes, and interrupted on the median 

 line. 



d. Outlines of abdomen subparallel 47. Synidotea nebuloxa Benedict. 



■d'. Outlines strongly arcuate 48. Synidotea angulata Benedict. 



c'. Without a ridge between the eyes. 

 d. Outline of abdomen subtriangular. 



e. Front not excavated 49. Synidotea con8olidata(S>tim^Bon). 



e'. Front excavated .50. Synidotea bicuapida (Oyren), 



d'. Outlines of abdomen ronnded. 



e. Length of abdomen equal to width at base. 



.51. Synidotea laticauda Benedict. 

 e'. Length of abdomen equal to one and one-half times width at base. 



52. Synidotea harfordi Benedict. 

 a'. Abdomen ]»ointed. 



b. Undulations of body not tubercular or spiny. 



c. Tubercle in front of eyes not margined 53. Synidotea nodulosa (Kr^yer). 



c'. Tubercle on the frontal margin and forming a i)art of it. 



54. Synidotea Iwvia Benedict. 

 b'. Undulations of the body tubercular and spiny, 

 c. Four spines on the front of the head; body spinous. 



55. Synidotea muricata (Harford), 

 c'. A wedge-shaped tubercle behind the frontal notch ; body tubercular. 



56. Synidotea picta Benedict. 



' Miera, .Journ. Linn. Soc. London, XVI, 1883, pp. 42, 43. 

 2 Benedict, Proc. Acad. Nat. Sci. Phila. (1897), p. 391. 



