ISOPODS OF NORTH AMERICA. 513 



GRAPSICEPON EDWARDSII Giard and Bonnier. 



Grapsicepon edwardsii GIARD and BONNIER, Compt. Rend. Acad. Sciences, CVII, 

 1888, p. 1. HANSEN, Ergebn. d. Plankton Exped. der Humboldt Stiftung, 

 II, 1895, p. 43. GIARD and BONNIER, Travaux de la Station Zool. de 

 Wiinereux, VIII, 1900, pp. 263-266, pis. vm, ix. 



localities. Florida stream; also Sargasso Sea. 



The adult female has a general globular form, flattened on the 

 dorsal surface and terminated at its posterior extremit} 7 by a group 

 of slender appendages with digitate edges; it measures 1.9 mm. from 

 the frontal border to the sixth segment of the abdomen. The head 

 forms a single and projecting mass, which is surrounded anteriorl}* 

 and on the sides by a large undulating anterior lamina or border; on 

 the inner side are found the very small, three-articulate first antennae, 

 which are situated some distance apart; the last two articles are fur- 

 nished with several small hairs having a rough surface; the second 

 pair of antennas are equally short, the first article is large, half con- 

 solidated with the head, and the other four articles decrease in size to 

 the last, which is furnished with several hairs; their surface presents 

 the same appearance as that of the first pair of antennae. The rostrum 

 is elevated and particularly distinct; from the notched point of the 

 inferior lip one can see the tip of the mandibles projecting, which is 

 in the form of the bowl of a spoon with the edge finely denticulate. 

 The maxilliped possesses an elongated palp terminating in little, short 

 hairs. The inferior margin of the head is cut up on both sides in a 

 pair of little lamella? of almost equal size, the cuticle of which is rough 

 and the extremity blunt. 



The first four thoracic segments are large and are in the form of 

 cushions; on their lateral margins are strong pleural bosses with con- 

 tours rather indistinct and with a rudimentary pleural lamella; the 

 three other segments are much narrower, their pleural lamella is 

 rather distinct, and the dorsal surfaces of the sixth and seventh seg- 

 ments are elevated in very sharp points in the median line of the body. 

 The ventral side of the thorax is completely hidden b}^ the incubatory 

 cavity, which is very regularly developed; the first of the oostegites 

 (lamellae) has an inner edge with several large digitations, and its pos- 

 terior part does not present a margin dentated or notched. The legs 

 are very reduced, which is in correspondence with the almost useless 

 part which they have to play in the fixation of the parasite, firmly 

 maintained in place by all the carapace of the host. The fourth of 

 these appendages is figured; under the rounded lateral margin, the 

 coxa shows a very solid chitinous armature, intended to move the 

 oostegite (lamella), which is attached there by the median nerve; 

 the basis is very large, flattened, and almost square; the ischium is 

 much narrower; the two following articles are fused and the propodus 

 2858905 33 



