BEACHTUEA FEO:\I TOEEES STEAITS. 43 



Hapalocakcintjs marstjpialis, Stimpson. (Plate 3. figs. 29-40.) 



Hapalocarcinus marsupiafis, Stimpson, Proc. Boston Soc. Nat. Hist. vi. 185G-59, p. 412 ; Semper, 

 'The Natural Conditions of Existence as they affect Animal Life' (London, 1881: Internat. 

 Sci. Series), pp. 216 >^t seq., fig. 64 c. 



Description of female. The carapace is soft and membranous, depressctl, broadly oval 

 in outline and truncated in front and behind. The breadth is equal to or a little less 

 than the length. The front is slightly dcflexed, obscurely tridentate, the median tooth 

 being sharp and separated by a shallow concavity on either side from the rounded lateral 

 corners. There are no true orbits, the space occupied by the eye being quite undefined 

 above and externally, while below the eye rests directly on the everted anterior margin 

 of the buccal frame. Tlie lateral margins of the carapace are rounded off dorso-ventrally 

 and evenly arcuate from before backwards. The posterior margin is concave and is about 

 three-fifths as long as the anterior margin. The surface of the carapace is perfectly even, 

 without any perceptible furrows, and is smooth except for a few minute and widely- 

 scattered setse. 



The abdomen consists of seven distinct segments, of which the first is partly 

 concealed under the posterior margin of the carapace. The first three segments 

 are visible from above, and are hardly more than half the width of the carapace. The 

 remaining four segments are bent under the body, and form a, broad oval plate about 

 equal in size to the carapace. The middle part of this plate, formed by the terga of the 

 four segments, is of somewhat firm consistency and is surrounded by a Avide membranous 

 border, which at the sides is folded inwards to form the lateral walls of the capacious 

 egg-pouch. The surface of the abdomen, like that of the carapace, is beset with minute 

 scattered sette. 



The ocular peduncles are relatively large, subconical, not lying in distinct orbits. The 

 corneal surface is facetted, but, in our specimens, devoid of pigment. The antennules ai-e 

 large and exserted, there being no fossettes for their reception. The basal joint is pro- 

 duced externally into a large conical process directed obliquely forwards and terminating 

 in a stout spine. The two succeeding joints are stout, cylindrical, and subequal in length, 

 tlie distal one carrying the two rudimentary flagella, each consisting of a few joints and 

 clothed with numerous long setae. The antennae consist of five joints, of which the first 

 is broad and triangular and the succeeding joints narrow, cylindrical, and successively 

 diminishing in diameter, the last being hardly thicker than the long seta which springs 

 from its tip. The buccal aiea is very large, extending across the whole width of the 

 carapace in front. Its anterior margm is sinuous, curving forwards on eithei- side below 

 the eye, and taking the place usually occupied by the inferior margin of the orbit. The 

 median part of the buccal margin approaches so closely to t\w base of the antennules 

 that an epistome can hardly be said to exist. The third maxillipeds do not nearly cover 

 the buccal cavity, and are widely separated from each other at the base by a semicircular 

 area of the sternum. The ischium is flattened, subtriangular in shape, widening 

 gradually from a narrow base, and having its antero-internal angle produced forwards, 

 rounded, and fringed with setse. The merus is articulated at the outer end of the distal 



G* 



