REPORT ON THE CRUSTACEA MACRURA. 



831 



Notostomus perlatus, n. sp. (PI. CXXXIV. fig. 2). 



Carapace having the dorsal surface deeply carinated, arched, and produced anteriorly 

 to a short, slender, straight rostrum, armed on the lower margin with five small denticles, 

 and on the upper with numerous smaller ones that are constant along the dorsal carina 

 to the posterior margin of the carapace. From the side of the rostrum a small carina 

 starts, and uniting with the orbital carina just behind the orbit, continues prominent to 

 the posterior margin of the carapace. A small and unimportant carina commences at 

 the posterior margin just below the orbital carina, and runs near and subparallel to it for 

 a short distance, and then dies out. From the second antennal tooth a carina runs 

 slightly downwards to the posterior margin, and between this and the inferior margin of 

 the carapace there exists the trace of a submarginal ridge. From the orbital to the outer 

 antennal carina a vertical ridge runs slightly obliquely downwards and backwards, being 

 formed by a sudden depression of the hepatic region. The lateral walls of the carapace 

 in this species therefore exhibit two obscure and two well-defined carinas on each side, or 

 nine in all. 



The carapace is smooth and the pleon corrugated ; the latter has all the somites 

 carinated, and the four posterior produced into well-defined teeth, of which that on the 

 third somite is larger than either of the three following. 



The telson is dorsally flattened and laterally compressed, and terminates in a sharp 



point. 



Length, entire, 



,, of carapace, 



„ of rostrum, 



„ of pleon, . 



„ of third somite of pleon, 



„ of sixth somite of pleon, 



,, of telson, 



Habitat.— Station 198, October 20, 1874; lat. 2° 55' N., long. 124° 53' E.; near the 

 Philippine Islands; depth, 2150 fathoms; bottom, blue mud; bottom temperature, 

 38 0, 9. One specimen, female. Trawled. 



This species in general aspect resembles Notostomus 2>citentissimus, from which it 

 may, however, be easily distinguished by its shorter rostrum, smooth carapace, the 

 smaller number of carinee and the larger dorsal teeth on the pleon. 



On close inspection there are observable other points of variation that are worthy of 

 consideration. 



Thedateral carina that starts from the inferodateral margin of the rostrum agrees 

 with the description of Notostomus gibbosus as given by A. Milne-Edwards, 1 in being 



] Ann. d. Sci. Nat, ser. 6, torn. xi. p. 7. 



