REPORT ON THE CRUSTACEA MACRURA. 



759 



Habitat— Station 232, May 12, 1875 ; lat. 35° 11' N., long. 139° 28' E.; Hyalonema- 

 ground, off Japan; depth, 345 fathoms; bottom, green mud; bottom temperature, 41 0, 1. 

 One specimen, female. Associated with Acanthephyra brachytclsonis. Trawl and dredge 

 both used. 



This species is interesting from its intermediate condition and from its resemblance in 

 some points to the genus Oplophorus. It has a sharp and prominent tooth on the 

 anterior margin of the first somite of the pleon, that is supported and strengthened by a 

 small tubercle ; this tooth, with the anterior margin, overlaps the posterior margin of the 

 carapace. The orbital tooth is wanting, but the first antennal is large and projecting, as 

 is also the second antennal tooth. There is no carina on the first and second somites of 

 the pleon, but the third, fourth, and fifth somites are slightly carinated, the carina 

 running to a posteriorly projecting tooth which decreases in size successively in each. 

 The sixth somite is dorsally grooved and terminates without a tooth in the median line, 

 but a well-formed tooth projects from the lateral margin half-way between the middle 

 of the dorsal surface and the lateral articulation of the rhipidura. 



The rostrum is narrow, long, depressed at the base, and then elevated to the apex, and 

 strongly dentate with sharp spine-like teeth that are more closely placed over the frontal 

 region than on the rostrum proper. 



The ophthalmopoda are large and pear-shaped and supported on a slender stalk. 

 They are situated at some distance from the median line, and on the outer side of the 

 ophthalmus support a prominent tubercle, while on the corresponding inner side there 

 are two small tubercles, and near the middle of the posterior surface, in a notch of the 

 ophthalmus, stands an oval-shaped ocellus. 



The first pair of antennae is deeply excavate and carries a broad and laterally elevated 

 stylocerite, the anterior margin of which is elevated into a transverse crest fringed with 

 hairs, the whole of which forms a deep cup in which the eye lies and rests protected. 

 The two succeeding joints of the antennae are short and the flagella reach to half the 

 lenplh of the animal. 



The second pair of antennas has the seaphocerite tapering to the apex, but the 

 squamous portion exists as a rounded extremity beyond the apical tooth, which is short 

 and strong ; at its base, standing on the second joint, is a long and powerful tooth, above 

 which is a notch into which the seaphocerite falls when laterally extended, but there is no 



