REPORT ON THE CRUSTACEA MACRURA. 599 



Loach's original figure in the Malacostraca Podophthalma Britannica does not so 

 represent it, but it is given in Sowerby's figure, and also in Adam White's, Professor 

 Bell's, and Sir Biehard Owen's. 



The specimens in the Challenger collection have not this feature developed beyond 

 that shown in Leach's figure, in which the central portion of the third somite is 

 posteriorly produced above and lies closely in contact with the dorsal surface of the 

 next succeeding somite. Many specimens were taken at the same station, which exhibit 

 variations that are interesting and perhaps important in the value they may have in 

 regard to the formation of specific character. A brief description of each variety is given 

 below. 



Spirontocaris spinus, var. a (PL CVI. fig. 1). 



Carapace dorsally carinated and armed with four or five large teeth, and seven or 

 eight very small ones on the rostrum, and with two teeth, sometimes a serrature, on the 

 lower margin. Pleon having the third somite arcuate and posteriorly produced to a 

 sharp point (Leach). 



Spirontocaris spinus, var. j3 (PI. CVI. fig. 2). 



Carapace dorsally carinated and armed with six large teeth which begin nearly at the 

 posterior margin of the carapace, and seven or eight small ones on the rostrum, and with 

 three teeth and no serrature on the lower margin. Pleon having the third somite 

 arcuate, and posteriorly produced and elevated to a large tooth (Owen, Mdne-Edwards, 

 BeU, Adam White). 



Spirontocaris spinus, var. y (PI. CVI. fig. 3). 



Carapace dorsally carinated and armed with teeth that commence about one-third 

 the length of the carapace from the posterior margin, and continue in a regular and 

 horizontal succession of eight to a short distance from the extremity of the rostrum, 

 when they gradually and rapidly decrease in size, in a series of four, to a sharp pointed 

 apex. The lower margin is armed with two or three teeth. The lower of the supra- 

 orbital teeth is smaller than the upper. Antennal tooth well developed. Fronto-lateral 

 tooth reduced to a point. Third somite of the pleon arcuate, and posteriorly produced to 

 a point in the median line. 



Spirontocaris spinus, var. 8 (PL CVIL). 



Carapace dorsally carinated and armed with five teeth, commencing rather more than 

 one-third its length from the centre of the posterior margin, and the rostrum with seven or 



