356 BUXiJETDr 54, n^ITED STATES IsATIONAL MUSEFM. 



S9. Genus IDOTHEA Fabrieius 1799. 



Flagellum of second antennge iiiu]ti-articulat.e. Maxillipeds with a 

 palp composed of four articles. Epimera of all the seg^ments of the 

 thorax, \rith the exception of the first, distinctlY separated from the 

 secfments. Abdomen composed of three seginents. with a suture line 

 on either side at the base of the terminal segment, indicating another 

 partly coalesced segment. 



ANALYTICAL KEY TO THE SPECIES OF THE GEXTJS IDOTHEA. 



a. Body slender, linear, filiionn. 



I. Terminal eegment of body truncate at ite posterior extremity; post-lateral an- 

 gles not prominent.. ..Idothea gradllima (Dana) 



h'. Terminal s^nient of body not truncate at ite extremity; post-lateral angles 

 prominent, 

 c. Post-lateral anglee of terminal segment prominent and separated by a not<th 

 from the triangular middle portion. 

 d. Terminal segment with middle portion obtuse and j>roduced at the apex in 



a small point. Lateral angles obtuse Idoiitea v.roioma i^thiypson 



d' . Terminal segment with middle portion of posterior extremity very acutely 



produced. Lateral angles acute Mother feivkeni, new pjjecies 



p'. Post-lateral angles not separated by a notch from the subtriangular middle 

 portion, which does not bear a tooth at the middle; the line from the apex 



to the lateral angle is straight JdotJiea reciiUnea Lockington 



a'. Body oblong-ovate. 



b. Terminal segment of body truncate at its extremity Jdothea metaWica Bosc 



//. Terminal segment of body not truncate at ite extremity. 

 c. The epimera of all the segments, from the second to the seventh inclusive, 



occupy the entire lateral margins of the s^ments Idothea baJtica (Pallas ) 



c^. The epimera of all the segments of the thorax, from the second to the 

 seventh inclusive, do not occupy the entire lateral margins of the segments. 

 d. Terminal segment of body with distinct and prominent post-lateral angles. 

 Basal article of the firsrt: pair of antennae very much dilated. 



JdoHiea ochoteiisis Brandt 



d\ Terminal segment of body without distinct post-lateral angles, the sides 



of the aljdomen tapering to a pointed extremity. Basal article of first 



pair of antennse not dilated Jdothea phosphorea Harger 



IDOTHEA GRACILLIMA Dana.. 



Stenosorna gracUlimum Dana, Proc. Acad. Is at. Sci. Phila., VII, 1854, p. 17-5. — 

 Stlmpson, Bost. JoTir. Nat. Hist., VI, 1857, p. 505. 



Jdo'liea gradllima Miebs, Jour. Linn. Soc. London, XVI, 188.S, p. 35. — Richaed- 

 soK, Proc. r. S. N'at. Mus., XXI, 1899, p. 844; Ann. Mag. Nat. Hist (7), 

 IV, 1899, p. 264; American Naturalist, XXXIV, 1900, p. 226; Harriman 

 Alaska Expedition. Crust., X, 1904, pp. 216-218; Proc. U. S. Nat. Mus., 

 XXVII, 1904, pp. 661-663. 



Lfx;(diti,es. — California: Bolinas, California. 



The description of this species given bv Professoi' Dana is very short 

 and rather vague. He describes the body as extremely slender and 



