PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 21 
and along the anterior and dorsal surface with small granular tubercles 
which become obsolete distally, are much less conspicuous than in 
C. cursor, and not definitely arranged in several longitudinal lines as 
in that species; the carpus is about two-fifths as long as the merus, 
slender and unarmed; the dactylus and the distal part of the propodus 
are wanting. The third ambulatory leg is a little longer than the first, 
fully as slender, and very much like it in lack of ornamentation and in 
the proportions of the segments. The posterior ambulatory legs are 
shorter than the merus in the third, and very slender. 
The abdomen is unarmed externally. The first pair of appendages 
reach to the second sternal somite, and the distal part of each appendage 
is straight to near the tip, which is curved outward and backward in a 
semicircular, blunt-pointed hook, and armed on the outer edge at the | 
base of the hook with a conspicuous tooth. 
Station 878, off Martha’s Vineyard, 1880, N. lat. 39° 55’, W. long. 70° 
54’ 15”, 142 fath., fine sand and mud; one specimen. The measure- 
ments in the first column of the accompanying table are from this speci- 
men, while those in the second column are taken from one of the type 
specimens of C. cursor. 
Measurements in millimeters and hundredths of length of carapax. 
C. gracilis. | C. cursor. 
Sb sags cece ob Saas SHS Hes Se Sea BSS CAA ee SESE SSRIS esa ie ef rot 
Length of carapax, including frontal teeth ... ieee 5.0 6.5 
Greatest breadth of carapax -................. 7.0 8.7 
Same in hundredths of length ..--..-.--.....- 140 134 
eaenniOl GHOUPCO 20 .- coaccei oe sc-ccasesnceps he are ays: oe 
ete er Beeiee mtn 2) me eliring= olaie nano nla! du daniaininls Sato te ace 3.1 3.6 
et aN ee ae eer omar (ae eeam ea mn pene aa geen wen aeenanaa sane 0.7 0.8 
REP eae OIA eee renie oo ec aeis o acum ee swanied eames olde oe acme ciascl 1.8 1.9 
Prana OU AL elt DMA LOL WOOP \ oo a. dencoe ae ca=naascne=soscemecsesscascsauconed 13. 0 11.5 
Ee MUI NIG Bere Oe as ees o tos ccc erat cae sum -\edanas cldce steese eee saaes 4.5 3.8 
aaa Pet UN Sone an seen oe a acces sat nance cine encn saeane res soetster eran 3.1 3.2 
Cui ti ee De" FEY ye a 55 BESS Oa eR ee oo SAE Ener 3.0 3.0 
enethiof second ambulatory leg ~--- 22... 2.2220 oo eam occ on nen sense see se- ea 5s ae 30.0 
Sasa MAIC TENT ee af SCS) a naaulein'g ooo cnin cade Me awocwlenn tebe cokes stole omine boas 11.0 10.5 
RE OC EU DUS (ie os Ie oe oie on one se saos stece ss scckee cds cuatesees <u Saeces ze ~ 4.2 4.7 
PE DNPOt SHEA POUUS cc c6 caso a= cick qomnscinee < cosqcen ocbareeecceaewsmocnse sek ous | 9.0 
enpth of dactylus ....-2....-:...... Se Fee Sables eee onicuapino eae sue canescens 5.4 
Length of third ambulatory leg ...........---..-- 18. 0 
Length of merus....-. 5.5 
Length of Pp owedus 5.5 
eNO Of MACUVIUG).2--2..0.>-2<-2-esiemaaeceese> ie ae 3.7 
Meneinon tonreh ambulatory leg: co. 105. foe sac cennccctanetiesscncsscsuee-- 5.5 
In C. cursor the teeth of the superior margin of the orbit are much 
larger than in gracilis and the sinuses smaller and more triangular. The 
anterior-lateral margin projects in a dentiform tubercle on the hepatic 
region, and back of this on the anterior part of the branchial region 
there is an acute and prominent tooth directed somewhat forward, and 
a smaller but acute tooth, just back of its base.* The first pair of 
*There is evident confusion in regard to the armament of the antero-lateral margin 
in Milne-Edwards’s description aboye referred to, for he says, ‘‘ Le bord latéral ne porte 
pas des dents, en avant du sillon post-hépatique les régions branchiales sont pourvues 
des quelques gros tubercules sur leur bord.” I have examined four of the original 
specimens of C. cursor returned to the Museum of Comparative Zoology, and they all 
have the antero-lateral margin armed, as here described, but agree in all other re- 
spects with Milne-Edwards’s brief description. 
