ISOPODS OF NORTH AMERICA. 



343 



FIG. 371. PLEUROPRION 

 MURDOCHI (AFTER 

 BENEDICT), x 8J. 



either side of the median spine, all three lying between the eyes. The 



median spine is a little anterior to the other two. On the posterior 



portion of the head are eight spines in a transverse 



row, four on either side of the median line. Four 



of these spines lie between the eyes, one behind each 



eye, and one lateral to each eye. There is also a 



spine on each of the antero-lateral projections. 



The lirst pair of antennae have the basal article large 



and dilated; the second article is almost as long as 



the first, but much more slender; the third is half 



as long as the second; the fourth is twice as long as 



the third. The first pair of antennae extend to the 



end of the second article of the peduncle of the 



second pair of antennas. The basal article of the 



second antennae is short, and does not extend beyond 



the basal article of the first pair of antennae; the 



second article is armed with three spines, and ex- 

 tends to the end of the first pair of antennae; the 



third article is one and a half times longer than the 



second, and is armed with two spines; the fourth is 



two and a half times longer than the third, and is 



unarmed; the fifth is twice as long as the third, and 



is unarmed. The flagellum is composed of three articles, the first of 



which is twice as long as the second; the terminal one is one-third 



as long as the second. The maxillipeds have a palp of five articles. 

 The first segment of the thorax has eight spines 

 in a transverse row, four on either side of the 

 median line. The second segment has six spines in 

 a transverse row, three on either side of the median 

 line. The third segment has eight spines in a trans- 

 verse row, four on either side of the median line, 

 and an additional spine on either side anterior to the 

 most lateral one. The fourth segment has two 

 transverse rows of spines, with a constriction 

 between the two rows. The first row has ten spines 

 in a transverse series, five on either side of the 

 median line, with three additional smaller spines, 

 one anterior and one posterior to the most lateral 

 spine, and one anterior to the spine next to the 

 most lateral one; the second row has six spines in a 

 transverse series, three on either side of the median 



line, with an additional smaller spine posterior to and between the 



two most lateral spines; there are also two spines anterior to the two 



median spines and back of the constriction, one on either side of the 



FIG. 372. PLEUROPRION 

 MURDOCHI. MAXILLI- 

 PED. x 27. 



