REPORT ON THE CRUSTACEA MACRURA. 241 



The ophthalmopod is long, subcylindrical, and has the ophthalmus scarcely larger 

 than the peduncle. 



The first pair of antennae has the peduncle as long as the rostrum, and carries two 

 small subcylindrical flagella. 



The second pair is biramose, the scaphocerite being longer but not broader than the 

 incipient flagellum. The oral appendages have not been determined, but the pereiopoda 

 are subequally developed; each of the three anterior pairs has an incipient chela, while 

 the last two are simple, and each pereiopod, like the gnathopoda, carries a long, well- 

 developed basecphysis. 



The pleopoda are all in an incipient condition, except the posterior pair, which 

 forms the outer plates of the rhipidura, and these are long, slender, and cylin- 

 drical. 



Another specimen very similar in form was taken in the Pacific on the 17th of July 

 1875, at Station 254 ; hit. 35° 13' N., long. 154° 43' W. 



The form represented on PL XLVII. fig. 1, was taken in the North Atlantic, April 

 29, 1876. 



Its length is about 10 mm. (0 - 4 in.), and yet in some features it appears to belong 

 to a younger stage than either of the preceding, as will be seen by the following 

 description : — 



The rostrum is as long as the carapace and is studded throughout its whole length 

 with small tooth-like points, and flanked on each side at the base, just over the antennal 

 region and within the frontal margin, with a long and strong tooth. The fronto-lateral 

 angle of the carapace is also produced to a strong spine-like tooth, and the lateral walls 

 are produced posteriorly beyond the pereion. The pleon has each somite dorsally armed 

 with a strong tooth, of which that on the second somite is much the largest, and is 

 studded with small denticles similar to those on the rostrum; the others are sharp- 

 pointed and smooth, that on the sixth somite being longer than any, except that on 

 the second. 



The telson is long and slender, dorsally flat, forked at the extremity, and furnished 

 on each side with a small denticle. 



The ophthalmopoda are well developed and pear-shaped. 



The first pair of antennae has a three-jointed peduncle, and supports two long and 

 slender flagella that reach a little beyond the extremity of the rostrum. 



The second pair of antennas carries a broad and well-developed scaphocerite, and a 

 long and slender flagellum that equals in length two-thirds of the animal, or twice that 

 of the rostrum. 



The two pairs of gnathopoda are developed as simple pediform appendages, and the 

 first three pairs of pereiopoda (fig. 1 k) are immaturely chelate, the dactylos being produced 

 more in the character of an immature joint, rounded and blunt at the apex : the pollex 



(ZOOL. CHALL. EXP. PAET LII. — 1886.) Fff 3] 



