348 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxv. 



and somewhat prismatic nodule (Plate XLVIII, fig. 2) which doubt- 

 less represents the basal segment of the antennules. 



Antenna? and maxillipeds unknown. Buccal cavity with parallel 

 sides, and very broad, equaling half the width of the carapace (Plate 

 XLIX, fig. 2). 



The chelipeds of the female (Plate XLVIII) are of moderate size, 

 subequal, and if extended, would measure in length about 1^ times the 

 width of the carapace. Merus thick, not much longer than wide. 

 Dorsal aspect of carpus about 1^ times as long as wide. Chela? nar- 

 row and strongly arcuate, fingers somewhat longer than palm, very 

 slender, grooved, their apposed edges meeting and edged with low 

 teeth. Low granular ruga? can be detected on the palm. The mar- 

 gins of the various segments appear to be bluntly rounded. 



Between the insertion of the cheliped and that of the first ambu- 

 latory, there is a considerable space (Plate XLVII, fig. 6; Plate 

 XLVIII, fig. 3) which tends to indicate the presence there of a large 

 afferent branchial opening. The first three pairs of ambulatory legs 

 are similar and of ordinary size; they are too fragmentary for descrip- 

 tion ; the merus is flattened, a cross section being nearl} T twice as long 

 as wide. The bases of these three legs occupy the entire length of 

 the after part of the sternum (Plate XLVII, fig. C>; Plate XLVIII, 

 fig. 3). The fourth and last leg, unfortunately missing, must obvi- 

 ously have a subdorsal position and be of slender build; the indica- 

 tions are that the legs of this pair were attached not at the outer mar- 

 gin of the broad sternal plate, as in Palicus Philippi," but nearer 

 together close to the outer edge of the abdomen (Plate XLVII, fig. 

 7; Plate XLIX, fig. 4), where the latter folds against the sternum, as 

 in Retropluma? 



The abdomen of the type female (Plate XLVIII, fig. 3) is as broad 

 as the length of the fourth to seventh segments inclusive and does not 

 nearly cover the sternum; second, third, and fourth segments sub- 

 equal in length; fifth a little longer; sixth the longest and twice as 

 long as the fourth; seventh broader than long, subtriangular. In the 

 male also ( Plate XLVII, fig. 6) the sixth segment is the longest but 

 may represent the fusion of two or more segments; the two segments 

 preceding it are subequal in length; the more proximal segment or 

 segments are crushed and indistinguishable. 



Measurements. — Type female (Plate XLVII, fig. T; Plate 

 XLVIII) : length of carapace, 24.5 mm.; width of same, 34.5 mm.; 

 width between anterior angles, 27.5 mm. Male (Plate XLVII, figs. 

 4-0): width of carapace, 25.7 mm.; width between anterior angles 

 (approximate), 20.7 mm. 



Associated with Archceopus antennatus at the same locality or 

 within the same formation at near-by localities is the following fauna. 



°Zweiter Jahresber. d. Vereins f. Naturk. in Cassel, 1 sns, j>. 11. 

 'Aiimt. Nat., XXVIII. 1894, p. 1044. 



