REPORT ON THE CRUSTACEA MACRURA. 913 



Ampluon provocatoris, n. sp. (PI. CXLVIIL). 



On the 7th of May 187G, in the Atlantic, south of the Azores, the largest and 

 apparently most mature specimen in the collection was taken. It differs from all the 

 larger specimens that were taken in the Pacific, by having no rostral tooth on the frontal 

 margin of the carapace, by having the fronto-lateral angles anteriorly produced to large 

 dimensions, and in having a tooth on the dorsal surface corresponding with the gastric 

 region. 



The carapace is long, narrow, and decreases slightly towards the posterior extremity, 

 it is half as long again as the pleon, including the telson, which equals the length of 

 the sixth somite. 



Length, entire, 



of carapace, 



of pleon, . 



of third somite of pleon, 



of sixth somite of pleon, 



of telson, . 



27 mm. (1-1 in.). 



15 



12 



1 



2 



3 



The dorsal surface of the carapace has the frontal margin nearly straight, and shows a 

 minute ocellus in the median line, behind which, halfway between the epistoma and the 

 frontal margin, stands a laterally compressed, dorsally erect and anteriorly pointed, well- 

 developed tooth. On the outer angle of the frontal margin stands an anteriorly directed 

 tooth that forms the inner canthus of the orbit, which exists on the outer side in the form 

 of a small emargination, the outer angle of which is rounded, beyond which the margin 

 slopes gradually to the fronto-lateral angle, which is defined by a strong tooth, from which 

 point the dorso-lateral margin, with a slight curve gradually narrows to the posterior 

 extremity of the pereion. The infero-lateral margin from the latero-frontal tooth curves 

 inwards and downwards just behind the oral appendages, and then recedes upwards and 

 backwards in a line corresponding with the dorso-lateral margin of the carapace. 



The pleon is narrow and gradually tapers to the extremity of the telson, which 

 under a high power is seen to divide into two small points, but which in the typical 

 specimen appears to be considerably worn down. The five anterior somites of the pleon 

 are short, while the sixth is as long as the preceding two, and the telson is subequal with 

 the sixth. 



The ophthalmopoda are short and do not reach beyond the lateral margins of the 

 carapace ; they are pyriform and supported on a slender but short pedicle that appears 

 to articulate with its own wide somite just beneath the frontal margin of the 

 carapace. The ophthalmus is long-ovate. 



The first pair of antennae has the peduncle broader at the base than at the distal 

 extremity and appears to be uniarticulate ; it carries at its extremity two flagella, the 



(ZOOL. CHALL. EXP. — PART LII. — 1888.) Fff 115 



