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



The ophthalraopoda suddenly enlarge from the pedicle and carry a prominent 

 tubercle on the inner distal extremity, just behind the ophthalmus, which is of a brown 

 colour in our preserved specimen. The other appendages do not exhibit features of any 

 peculiar specific value. 



Length, entire, .... 



„ of carapace, 



,, of rostrum, 



„ of pleon, 



„ of third somite of pleon, including tooth ( 



„ of sixth somite of pleon, . 



,, of telson, .... 



Habitat.— Station 191, September 23, 1874 ; lat. 5° 41' S., long. 134° 4' 30" E.; 

 off the Arrou Islands ; depth, 800 fathoms ; bottom, green mud ; bottom temperature, 

 39° "5. One specimen, male. Trawled. 



Station 213, February 8, 1875 ; lat. 5° 47' N., long. 124° 1' E.; near the Phdippine 

 Islands ; depth, 2050 fathoms ; bottom, blue mud ; bottom temperature, 38 c, 8. One 

 specimen, male. Trawled. 



Length, 71 mm. 



Station 214, February 10, 1875; lat. 4° 33' N., long. 127° 6' E.; south of the 

 Philippine Islands ; depth, 500 fathoms ; bottom, blue mud ; bottom temperature, 41° - 8. 

 One specimen, female (1). Trawled. 



Length, 55 mm. 



& 



This species may easily be recognised by the shortness of the rostrum, which scarcely 

 reaches beyond the extremity of the peduncle of the first pair of antennse, and by the 

 largely elevated character of the carina on the third somite of the pleon, the terminal 

 point or tooth of which, instead of being directed straight backwards, is depressed. 



The ophthalmi (fig 3a) are small and of a brown colour ; the stalk is a little com- 

 pressed on the upper side and the inner angle is anteriorly produced to a tubercle that 

 encroaches upon the ophthalmus, but the ocellus, which is present in so many of these 

 species, is small and connected with the ophthalmus. 



There is nothing besides very distinguishing in the character of the species, except 

 that the three posterior pairs of pereiopoda have the inferior margin armed with teeth 

 that are longer and more spinous than usual. 



Observations. — The distinction between the specimens, besides that of dimensions, 

 appears to depend upon the character of their habitats. That which was taken from 

 the deeper water is softer in its external tissue. 



A comparison of these three specimens with each other, and with the genera 

 Tropirinus and Hymenodora, shows how gradually varieties pass into species. 



