44 



Si/nopsis of the Indian species. of Benthesicymus. 



I. Fifth abdominal tergum without a spine : rostrum 3-toottied ... B. investigatoris. 

 II. Carina of the 5th abdominal tergum produced to form a long 



liooked spine : rostrum 2-toothed ... ... ... B. Bartletti. 



20. Benthesicymus investigatoris, Anderson. 



Benthesicymus im-estigatoris, Alcock and Anderson, Ann. Mag. Nat. Hist., April 1899, p. 282. 

 ILLUSTRATIONS OF THE ZOOLOGY OF THE INVESTIGATOR, CRUSTACEA PL. XLI. FIG. 2. 



Glabrous. Rostrum not reaching to the end of the eye, 3-toothed dorsally, 

 produced as a sharp carina as far as the well-cut cervical groove only. A ridge 

 defines the upper limit of the branchial region and ends, after a break, at a strong 

 post-antennal spine, the only spine on the carapace. 



The 5th and 6th and the posterior three-fourths of the 4th abdominal 

 terga are carinated. The 6th abdominal somite is nearly twice as long as the 

 5th. The telson is very much shorter than the endopodite of the caudal fan. 



Eyes somewhat deficient in pigment, little Avider than their stalk. 



Antennular flagella very long, the upper one longer than the entire body 

 and much thickened in about its basal fifth. Antennal scale nearly twice as 

 long as the antennular peduncle, thickened at tip in the male. 



External maxillipeds stouter than any of the legs, not quite as long as the 

 3rd pair of legs : their dactylus is short and somewhat hooked, and ends in a 

 pair of little spines : in the male the hooking of the dactylus is more marked 

 than in the female, and in addition to the two terminal spines there is a little 

 tubercle ending in a pair of spines near the base of this joint. The flagelliform 

 5th pair of legs reach a good way beyond the tip of the antennal scale. 



The exopodites of the 1st pair of abdominal appendages are about as long 

 as the carapace without the rostrum, between them in the middle line is an 

 extremely prominent uncate tooth, more prominent in the male than in the 

 female. 



The " thelycum " consists of a tubercle between the 3rd pair of legs 

 followed by two transverse bands lying respectively between the 4th and 5th 

 pairs of legs, the first of these bands being sinuously notched anteriorly, the 

 second being simply notched posteriorly. 



The " andricum " consists of a pair of subtriangular leaves which appear 

 to interlock only when in use. 



In the type specimen the rostrum and carapace are 24 millim. long, and 

 the abdomen is 54 millim., measured in the mid-dorsal line. 



Andaman Sea, 400-200, 370-419, 498, and 640 fathoms : Gulf of Manar 

 597 fathoms. 



Reg d.Nos. ^ (Types of the species) : 8 ^: 3 ^- 2 : ' : !Sj* : !* 



