REPORT ON THE CRUSTACEA MACRTJRA. 201 



tooth on the basis and another on the ischium, and there is one on the basis of the second 

 pair, but in Penseus anchoralis there is one only on the basis of each pair of legs. 

 The telson in Penseus velutinus is as long as the outer plates of the rhipidura, and is 

 laterally armed with four movable spines and one rigid tooth, while in Penseus anchoralis 

 it is one-fourth shorter, and is armed with three small spines of so little importance that 

 they are only appreciable by a lens under certain aspects. In addition, the form of 

 the petasma in the male, and of the thelycum in the female, together with the unusual 

 presence of two long ventral teeth between the coxae of the second pair of pereiopoda, go 

 to make up the characters of two very distinct species of which the general external 

 appearance is almost similar. 



They appear not to be inhabitants of deep water, inasmuch as they have not been 

 taken at a greater depth than 50 fathoms, and their range appears to be from Japan in 

 the north to the northern shores of Australia in the south. 



Penseus philippinensis, n. sp. (PL XXXV. figs. 2, 3). 



Tomentose ; no carina on the posterior half of the carapace. Eostrum horizontal, 

 straight in the male, a little elevated in the female, armed with seven teeth that become 

 smaller and further apart as they approach the extremity, and one very small tooth 

 posterior to the rest and more remote, situated on the gastric region. Pleon laterally 

 compressed and produced to a faint carina from the second to the sixth somite, where 

 it culminates in a small point at the posterior extremity. 



Ophthalmopod short, ophthalmus large, not cmite half the length of the rostrum. 

 Peduncle of the first pair of antennas scarcely reaching to the extremity of the rostrum. 

 Flagella short, slender, and rather longer than the last two joints of the peduncle. 

 Stylocerite slender, sharp-pointed and curved upwards at the extremity, prosartema 

 reaching a little beyond the extremity of the eye. 



Second pair of antennse long, slender, having the scaphocerite equal in length to 

 the rostrum and subecmal to the peduncle of the first pair of antenna?, and having the 

 antero-external tooth parallel with the distal margin of its foliaceous plate. The 

 pereiopoda are not very long, none reaching, when extended forwards, as far as the ex- 

 tremity of the rostrum, and the dactyli of the last two pairs are short. The first pair 

 carries a tooth on the basisal and one on the ischial joint, but there is none on the 

 second ; a deep depression exists in the male between the coxa? of the two or three 

 posterior pairs, in which the petasma, attached to the first pair of pleopoda, lies. The 

 petasma (fig. 3") is folded longitudinally in a columnar form, somewhat resembling the 

 same organ in Penseus velutinus, but the shaft on the left side, being the longer, is 

 folded over in a coil in front of that of the right. The second pair of pleopoda has the 

 complementary button-shaped appendage consisting of a long, curved, tubular process 



