DECAPODS 117 



Bailey Harbor, Alaska Peninsula [Albatross). 



Coal Harbor, Unga Island, Shumagins, 3 fathoms (\V. H. Dall). 



Also occurs along the eastern coast of North America, from East 

 Florida (Say) northward. 



It becomes necessary to separate the common Crangon of the Atlantic 

 and Alaskan coasts of North America from the form found in Europe. 

 These two species have usually been combined under the name Crango?i 

 crangon (Linnaeus) or C. vulgaris Fabricius. 



In Crangon crangon (of Europe) the antennal scale is wider at its 

 distal end, and that margin, although convex, trends forward toward the 

 inner angle. The spine is shorter than the distal width of the blade. 



In Crangon septemspitwsa Say (of America) the scale is narrower at its 

 distal end, and that margin, although convex, does not trend forward 

 toward the inner angle, but rather slopes backward. The spine is as 

 long as, or longer than, the distal width of the blade. 



CRANGON ALBA Holmes. 



Crangon alba Holmes, Occas. Papers Calif. Acad. Sci., vii, 174, 1900. 

 Monterey, dredged. 



A short stout species. Carapace about two fifths as long as abdomen. 

 Rostrum broader than in C. nigricatida. The first segment of the anten- 

 nule exceeds the process on the outer side of its base ; 

 inner flagellum exceeding the antennal scale; outer 

 flagellum shorter than the scale. Blade of scale with 

 very oblique inner margin, the tip scarcely wider than 

 the adjacent portion of the spine; spine extending 

 considerably beyond the blade. Scale 

 ) about three fourths the length of carapace. ,f "^- 56. Crangon 



^ " ■^ alba. S . San Diego. 



Maxillipeds reaching the end of the '^•Dorsal view of orbital 



Fig. 57. Crangon.. . region (x 4)- i^. Acicle 



alba. Chela of ? blade, the antepenult segment much ex- *x ^'• 



(X 2f). San Diego. . 



panded. The first pair of feet reach to the middle of 

 the last joint of the maxillipeds ; the hand is very stout, wider than in 

 C. nigricauda, the length being two and one fourth times the width 

 measured from the inner base of the immovable spine ; the anterior 

 margin is more longitudinal than transverse. 



The segments of the abdomen are smoothly rounded; the sixth is 

 rounded beneath, not grooved ; the seventh is not sulcate above. 



Dimensions. — An ovigerous female (station 3679) measures 48 mm. 

 long, carapace 12.5 mm., scale 9.7 mm. 



Distribution, — From Vancouver Island, British Columbia, to San Diego, 

 California, to a depth of 47 fathoms, at the following localities : 



