420 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 83 



about 0.2 mm and very slender, armed distally underneath with 

 several spines; tarsus II stout, curved ventrally, 0.7 mm long, 

 armed dorsally with a row of short spines, ventrally in proximal 

 part armed with three or four heavy curved spines, distally with 

 several small spines ; claw 0.3 mm long, curved, untoothed ; auxiliary 

 claws slender but over half as long as claw. Genital apertures of 

 male occur on distinct high tubercles on ventral distal margins of 

 second coxae of two posterior pairs of legs; genital apertures of 

 female occur on slightly swollen areas in a position similar to male 

 on all four pairs of legs. 



Abdominal process slender, cylindrical, pointing posteriorly but 

 slightly bent upward, about three-fourths as long as proboscis; 

 armed near tip with a few spines. 



Immature specimens possess well-developed chelae and have been 

 found ranging in size from specimens only half as large as mature 

 specimens to fully grown specimens. Among smaller individuals 

 the ovigera are entirely undeveloped and are indicated only by a bud 

 in front of anterior pair of walking legs ; in large specimens ovigera 

 almost as complete as in mature females. It seems impossible to 

 distinguish males and females among innnature specimens. 



Considerable variation is noted in the external appearance of in- 

 dividuals of Ammothea discoidea^ owing to differing stages of 

 ecdysis ; specimens that had not recently molted when collected pos- 

 sess a tougher integument and stiffer and more visible spines than 

 those that had just molted. The living animal varies from a deep 

 pink to white; preserved specimens lose the pink color and vary 

 from tan to white. 



Measureinents. — Body, including proboscis, 2.8 mm; proboscis 1.1 

 mm; trunk 1.1 mm; abdominal segment 0.7 mm; lateral process 0.5 

 mm long ; eye tubercle 0.25 mm high. 



Types. — Holotype : Male specimen collected with a group of males, 

 females, and immature specimens dredged south of McNeils Island, 

 Puget Sound, July 24, 1934, U.S.N.M. no. 71500. Paratypes: 

 Males, females, and immature specimens dredged off Fosdick 

 Point, Puget Sound, July 1935; immature and female specimens 

 dredged off Blake Island, July 8, 1935; males, females, and imma- 

 ture specimens dredged off Lake Hancock, August 10, 1935; males, 

 females, and immature specimens dredged between McNeils Island 

 and Bahl Passage, July 8, 1935; specimens from off Caldron Rock 

 (70 meters), July 10, 1935; females dredged off Vashon Point, July 

 24, 1934; immature specimens dredged off Fosdick Point, July 23, 

 1934; males, females, and immature specimens dredged from 40 

 meters off McNeils Island and Bahl Passage. 



Remarhs. — Ammothea discoldea is most nearly related to A. Jati- 

 frons Cole (1904, p. 263), a species that occurs around Unalaska and 



