822 THE VOYAGE OF H.M.S. CHALLENGED. 



Telson as long as the sixth somite, tapering, furnished with seven separate, minute 

 spinules on the dorso-lateral angles, and subequal in length with the outer rami of the 

 rhipidura. 



The male is more slender, but corresponds with the female in general features. 



Habitat.— Station 218, March 1, 1875; lat. 2° 33' S., long. 144° 4' E.; off New 

 Guinea; depth, 1070 fathoms; bottom, blue mud; bottom temperature, 36°"4. Two 

 specimens ; one male, one female. Trawled. 



This species corresponds in several respects with Nematocarcinus productus and 

 Nematocarcinus parvidentatus, but differs in the relative lengths of the rostrum and 

 carapace, as may be seen from the measurements given under each species. 



Thus in Nematocarcinus intermedins the rostrum is two-thirds the length of the 

 carapace, one-half in Nematocarcinus productus and about one-third in Nematocarcinus 

 parvidentatus ; on the shortest rostrum there are twenty-two teeth, and on the longest 

 there is just the same number, although the rostrum is three times as long. 



I am therefore compelled in the present state of our knowledge to consider the three 

 to be distinct species. 



The male specimen has the rostrum broken, which is to be regretted, since I am there- 

 fore unable to compare it with a smaller specimen that was taken in the same haul, and 

 which I believe to belong to Nematocarcinus tenuipes, which differs from Nematocarcinus 

 parvidentatus in the possession of a small tooth on the under surface of the rostrum near 

 the apex, a feature that I sometimes think may be sexual rather than specific. 



Stochasmus, 1 n. gen. 



Carapace one-third the length of the animal, dorsally compressed anteriorly, and 

 produced to a rostrum that is armed with a series of spinules on the upper surface ; 

 furnished on the frontal margin with an antennal tooth and with one at the fronto-lateral 

 angle. 



Pleon laterally compressed and dorsally smooth. First somite as deep as the second, 



1 oTo%txiifios, a conjecture. 



