DECAPODS 73 



Male.— As, compared with the female, the teeth of the median carina 

 and rostrum are much smaller and more appressed, sometimes obsoles- 

 cent, the rostrum less deep and more horizontal ; the antennular acicle 

 does not reach the end of the second segment of 

 the peduncle ; the spine of the antennal scale falls 

 short of the end of the blade. 



Dimensions. — $ , length (approximate) 38 mm., 

 length of carapace and rostrum 13.6 mm., of ros- 

 trum 6 mm. 



Distribution.— Arctic Alaska, Aleutian Islands fig. 27. s/>i^^^^Z^ daiu 

 to Sitka. ^<^ ^f A""- 



a. Side of carapace of i . 



Although this species appears to be not rare ''■ side of carapace of 9. 

 in Alaska, it has been collected almost exclusively by Dr. Dall, who ob- 

 tained it at 17 stations along the Aleutian Islands and eastward to Port 

 Etches, 6-20 fathoms; oif Cape Sabine, 13 fathoms; and 15 miles ofiE 

 Cape Krusenstern, 14 fathoms. 



Sitka, 2 specimens (Harriman Expedition, W. R. Coe, collector). 



SPIRONTOCARIS POLARIS (Sabine). 



Alpheus polaris Sabine, Supplement to Appendix of Parry's [First] Voyage, 



p. ccxxxviii, pi. II, figs. 5-8, 1824. 

 Hippolite borealis James C. Ross, in John Ross, Appendix to Narrative of 



Second Voyage in Search of a North- West Passage, p. Ixxxiv, pi. B, fig. 



3, 1835 ( 3 ). 

 Hippolite polarts James C. Ross, op. cit., p. Ixxxv ( ? ). 

 Hippolyte St. Pauli BRANDT, Middendorff's Reise Sibir., Band II, Zool., 



Theil I, Krebse, p. 118, pi. v, fig. 19, 1851. 

 Hippolyte cultellata NORM AN, Rept. Brit. Assoc. Adv. Sci., 1866, p. 200 



(1867) (= H. polaris, teste Norman, Museum Normanianum, ill, Crus- 

 tacea, p. 8, 1886). 

 Hippolyte polaris Smith, Trans. Conn. Acad. Arts Sci., v, p. 80, pi. xi, figs. 



1-4, 1879. 

 Hippolyte Amazo Pfeffer, Jahrb. Hamburg. Wiss. Anst., iii, 46, plate, 



figs. 7a, 7b, 1886. 

 Hetairus gaitnardii ^\t:^, Challenger Rept., Zool., xxiv, 611, pi. cix, fig. 



2, 1888 (not Hippolyte gaimardii Milne Edwards). 

 Hetairus tenuis Bate, op. cit., 613, pi. cix, fig. 3. 

 Hetairus debilis Bate, op cit., 615, pi. CIX, fig. 4. 



Professor Smith {loc. cit.) sets forth the variations in the sexes, in the 

 number of rostral spines, and in the aculei on the telson. He states that 

 "the disappearance of the dorsal teeth of the rostrum is evidently a 

 character peculiar to, but not characteristic of, the adult male." In the 

 series of specimens from the North Pacific and Bering Sea this is not 

 the case, as the majority of the females from those locaUties are devoid 

 of superior rostral teeth. This series also exhibits other variations. The 

 body and thoracic feet are usually stouter, the antennal scale shorter and 



