Pacific Coast of North America. 267 



c'. Tubercles free at bcose 46. S. erosa, Benedict. 



b'. No spines or tubercles overhanging 

 frontal notcli. 

 c. With a low ridge arising between 

 the eyes and interrupted on the 

 median line. 

 d. Outlines of abdomen subparallel. 47. S. nebulosa, Benedict. 



d'. Outlines strongly arcuate 48. S. aiiyulata, Benedict. 



c'. Without a ridge between the eyes. 

 ' d. Outline of abdomen subtrian- 



gular. 



e. Front not excavated 49. & consolidata (Stimpson). 



e'. Front excavated 60. -S. bicuspida (^Owen). 



d'. Outlines of abdomen rounded. 

 e. Length of abdomen equal to 



width at base 51. S. laticauda, Benedict. 



e'. Length of abdomen equal to 

 one and one-half times 



width at base 52. S. Harfordi, Benedict. 



a'. Abdomen pointed. 



b. Undulations of body not tubercular 

 or spiny. 

 c. Tubercle in front of eyes not mar- 

 gined 53. S. nodulosa (Kroyer). 



c'. Tubercle on the frontal margin and 



forming a part of it 54. 5. Icevis, Benedict. 



b' . Undulations of the body tubercular 

 and spiny. 

 c. Four spines on the front of the 



head ; body spinous 55. S. muricata (Harford). 



c'. A wedge-shaped tubercle behind 

 the frontal notch ; body tuber- 

 cular 56. S. ptcta, Benedict. 



Mr. Adrian Dollfus, in his paper on " Les Idoteidge des 

 Cdtes de France"*, lias wrongly confounded Spiidotea, 

 Harger, with Stenosoma, Leach. Synidotea can by no means 

 be considered a synonym of Stenosoma, as anyone who is 

 familiar with the two genera will undoubtedly admit. It 

 differs from Stenosoma in the consolidation of the epimera 

 with the segments. The epimera are firmly and perfectly 

 united with the segments, and the only trace or indication of 

 a separation is represented in the anterior segments by a 

 slight and almost imperceptible notch in the posterior margins, 

 halfway between the lateral margin and the median line of 

 the body, and in the three posterior segments by a very faint 

 line. In Stenosoma all the epimera are very distinct from 

 the segments. 



* ' Feuille des Jeuues Naturalistes,' 1895. 



