530 



THE VOYAGE OF H.M.S. CHALLENGER. 



Parathanas, n. gen. 



Animal robust. Carapace about one-third of its length. Eostrum short. Pleon 

 having the sixth somite nearly as long as the two preceding. Telson half the length 

 of the sixth somite. 



Ophthalmopod short, orbicular. 



First pair of antennae considerably longer than the ophthalmopoda and terminating in 

 two flaefella. 



Second pair carrying a long and narrow scaphocerite. 



First pair of pereiopoda robust, chelate ; second pair slender, chelate, having the 

 carpos multiarticulate ; third and fourth pairs short and simple ; fifth pair very long and 

 slender, and (probably) styliform. 



There is only one perfect specimen in the collection and that is immature. It is 

 closely allied to Athanas, but differs from that genus in having only two simple flagella, 

 one of which is very short, attached to the extremity of the first pair of antennae, and in 

 having the posterior pair of pereiopoda longer than the preceding. 



Geographical Distribution. — The two species were taken near the Celebes Islands. 



Parathanas decorticits, n. sp. (PI. LXXXIX. fig. 3). 



Animal moderately robust. Rostrum short, dorsally smooth and pointed. 



Ophthalmopod orbicular, scarcely longer than the rostrum. First pair of pereiopoda 

 larger than the second ; second more slender, but not longer than the first ; posterior pair 

 of pereiopoda longer than the others. 



Telson pointed. 



Length, entire, .... 

 of carapace, 

 of rostrum, 

 of pleon, 



of sixth somite of pleon, 

 of telson, 



Habitat. — October 23, 1874; taken off Sibago, Sam 

 80 fathoms. One specimen. 



G mm. (0-23 in.). 



2 



0-5 



4 



1-3 



1 



boangan, Philippine Islands, in 



The animal generally is tolerably robust. The carapace, which is 2 mm. long, is 

 rather more than one-third the length of the animal, measured from the frontal margin 

 to the extremity of the telson ; the rostrum is short, being about one-fourth the length 

 of the carapace, and is dorsally flat, smooth, and pointed. 



The pleon has the anterior somites shorter than the posterior, of which the fourth 



