REPORT ON THE CRUSTACEA MACRURA. 741 



of the first and second pairs of antennae. The second antennal tooth is also small, and 

 continued as an angular ridge posteriorly to the hepatic fissure. 



The pleon is carinated, the first somite is smooth, and separated into two portions, 

 the anterior portion is equal in length to the posterior, and passes under the dorsal 

 surface of the carapace, so as to be entirely hidden when the animal is extended, and the 

 coxal plate overrides the lateral walls of the carapace, and has the anterior margin, which 

 is as deep as the carapace, excavate to correspond with the curve of the latter. The 

 second somite is also dorsally divided into two portions, of which the anterior passes 

 beneath the first when the animal is extended ; it is dorsally carinated on the posterior 

 division, the carina commencing and terminating abruptly, the posterior extremity in the 

 median line being emarginate to admit the anterior edge of the carina of the following 

 somite. The third somite is also divided into two portions, of which the anterior, 

 that passes under the preceding somite, is much smaller than the posterior, which is 

 strongly carinated, the carina commencing abruptly with the posterior division, and con- 

 tinuing posteriorly to a small, laterally compressed tooth. The fourth and fifth somites 

 resemble the third, but have no anterior division, and the dorsal carina and dental 

 elevation are less conspicuous. The sixth somite is nearly as long as the preceding two, 

 and like them is dorsally carinated and posteriorly produced to a tooth, and the coxal 

 plates are either wanting or reduced to a minimum condition, as the lateral walls of the 

 somite are continuous with the ventral surface. 



The telson (fig. lz) is narrow, tapering, and considerably longer than the sixth somite, 

 and not much shorter than the carapace ; it is dorsally grooved from just beyond the 

 base to just within the apex, the sides are longitudinally depressed suddenly, and armed 

 on the distal half with nine separate small spinules, and terminally with four. 



The ophthalmopoda (fig. la) are somewhat pyriform and supported upon a small pedicle, 

 from which they suddenly enlarge ; they are slightly compressed laterally, and increase in 

 size as they approach the ophthalmus, which is orbicular, and separated by a constriction 

 from the base on which it stands, and which projects to a small tubercle on the inner side, 

 and carries a small and somewhat imperfect ocellus on the posterior part, connected by a 

 thin line of pigment with the ophthalmus. 



The first pair of antennae (fig. lb) has the peduncle short or about a fourth of the 

 length of the rostrum. The first joint is deeply hollowed on the upper surface to receive 

 the ophthalmopod, and carries a stylocerite that is shorter than the first joint, and has the 

 outer wall perpendicular, the apex of which is suddenly narrowed to a small sharp tooth, 

 and the base strengthened by two small tubercles that project upon the dorsal surface 

 between the outer canthus of the orbit and the first antennal tooth, against which the 

 outer surface of the stylocerite presses and receives sujyport when the antennas are 

 directed outwards. The second and third joints are short and cylindrical, and support 

 two flagella, of which the outer is much larger in both sexes than the inner ; the latter is 



