830 THE VOYAGE OF H.M.S. CHALLENGER. 



Notostomus japonicus, n. sp. (PI. CXXXV. fig. 1). 



Carapace having the dorsal carina horizontal and but little elevated, serrate along the 

 surface from the posterior extremity to the anterior (the rostrum is broken off just 

 anterior to the ophthalmopoda). Each lateral surface has three carinas ; the semicarina is 

 represented by a longitudinal groove parallel with the posterior half of the orbital carina. 

 The inner orbital margin is not confluent with the orbital carina, and a small ridge runs 

 from the upper margin of the rostrum and dies out above the frontodateral region. 



The first pair of antennas has a long and sharp stylocerite ; the outer flagellum is 

 broad and flat towards the base, and then narrows abruptly to a slender termination. 



The second pair of antennas carries an ovate scaphocerite that is armed on the 

 outer distal margin with a long and sharp tooth. 



The telson is dorsally grooved in its entire length, and is shorter than the inner 

 lateral plate of the rhipidura. 



Habitat.— Station 235, June 4, 1875 ; lat, 34° 7'N., long. 138° 0' E.; south of Japan ; 

 depth, 565 fathoms ; bottom, green mud; bottom temperature, 38°"1. One specimen, 

 male. Trawled. 



This species is rather more compressed and less elevated dorsally than the other 

 species ; the median carina is nearly straight, and the outer antennal carina is more than 

 usually distant from the orbital, and is nearly parallel with the inferior margin of the 

 carapace. 



The rostrum is broken off in the only specimen taken. 



The surface of the animal is corrugated all over, more coarsely on the pleon and dorsal 

 surface of the carapace than along the lateral walls. The broad ventral plate-like surface 

 posterior to the last pair of pereiopoda is shorter than in female forms ; the inner branch 

 of the first pair of pleopoda is broad, short, and submembranous, having the stylamblys 

 reduced and closely associated with its margin, the extremity furnished with numerous 

 cincinnuli, and the margin with short stiff spines. 



The specimen may not improbably have been a wanderer from deeper water, since 

 where it was taken the ocean rapidly deepens from the 100-fathom coastdine to 3000 

 fathoms; and the bottom temperature was only 0°'l above that at 1425 fathoms at 

 Station 195 in the Sea of Banda. 



