386 



BULLETIN OF THE BUREAU OF FISHERIES. 



Fig. S. — Crangon heterochtsln . 

 a. Front of caraiiace; b, small chela. 



Crangon heterochslis (Say). PI. xxvi, fig. 6. 



Alpheus heterochalis Say, 1818, p. 243: Milne-Edwards, 1837, t. n, p. 356; Kingsley, 1878-79, p. 329,- Herrick, in Brooks 

 and Herrick, 1892, p. 372; Rathbun, 1901, p. 107; Coutiere, 1910, p. 485. 



Carapace slightly more than half as long as abdomen, slightly compressed and without grooves; 

 front produced into a rounded lobe above each eye; rostrum carinate, the carina not extending back 



as far as base of eyes talks and the tip falling short of second article 

 of antennule; rostro-orbital depressions passing gradually into 

 dorsal surface. Abdomen compressed, smooth, tapering; telson 

 with subparallel sides and rounded tip; the four movable spines 

 of the upper surface and those of the distal border relatively 

 much weaker than in C. packardii. 



Eyes relatively small, covered by the carapace. Antennules 

 with inner branch filiform, about half as long as antenna; outer 

 branch with proximal half expanded. Antennae a little longer 

 than body, very slender; scale with a strong apical spine which 

 slightly exceeds the antennular peduncle; basal segment with a 

 rather weak spine below. Chelae very unequal; the larger one 

 much distorted, the upper and lower siufaces with irregular shal- 

 low grooves and the outer and inner margins deeply notched 

 near base of fingers; dactylus very broad and heavy, strongly 

 curved and with a very large basal tooth. Smaller chela, in the 

 male, mth the dactylus peculiarly flattened and expanded on 

 its outer surface; fingers of small chela, in both sexes, much weaker, less ctirved, and more hairy 

 than in the large chela. Carpal articles of second pair of legs diminish as follows: First, second, fifth, 

 third, fourth. 



Length of a male, 40 mm.; carapace, 13 mm.; a female, 50 mm. 



Color, dark, translucent sea green, slightly flushed with purple on sides of carapace; with white 

 markings on chelipeds; walking legs pale vermilion; tips of uropods blue, with a narrow border of 

 orange on distal margin, the outer blade having in addition a patch of vermilion just above the blue, 

 and a narrow white border; articular surfaces and points of ab- 

 dominal segments and a small streak along cervical groove white. 



This species of snapping shrimp, while not as common in the 

 Beaufort region as C. packardii, is far from rare and is locally often 

 quite abtmdant. Its favorite habitat is around the edges of oyster 

 reefs where it digs large burrows in the mud or conceals itself 

 among the shells. When captured the loud snapping sound it 

 makes, which is comparable to the cracking of a small whip, is sure 

 to command attention. Females bearing their large masses of clear 

 apple-green eggs have been taken early in July. An isopod para- 

 site (Probopynis alphei Richardson) is occasionally found in the gill 

 chamber of this snapping shrimp. 



Crangon armillatus (H. Milne-Edwards). PI. xxvn, fig. i. 



Alpheus armiUaius H. Milne-Edwards, 1834-1840, t. n, p. 354; Couti&re, 1910, 

 p. 485. 



Very closely resembling C. heterochzlis except in the rostrum 

 and the small chela of the male. 



The rostrum has the form of a narrow crest which, just behind 

 the eyes, widens abruptly into a triangular area the borders of which are slightly concave and very 

 distinctly limit the rostro-orbital depressions, even slightly overhanging them in adult specimens. 



The dactylus of the small chela of the male lacks the setose crests and expanded external siuface so 

 characteristic of C. heterochcelis . 



By Couti^e this species is said to be abtmdant and widely distributed along the Atlantic coast 

 and often to accompany C. heterochcelis. At Beaufort, however, it does not appear to be common, a 

 single specimen, dredged by the FuAHa7(;fe, being foralong time the onlyoneinthe laboratory collection, 



Fig. 9. — Crangon armillatus. 

 Front of carapace; 6, small chela. 



