250 Southern Cross. 



species, and it will be amply sufficient for all practical purposes to 

 point out the differences. 



First antenna. The terminal joint is shorter than the two 

 preceding together. 



Second antenna. The first joint is very small and the second 

 about twice the size, with four small blunt spines. The third joint 

 is long and bears three or four blunt spines and a few long setae on 

 the opposite side. The fourth joint bears one or two small spines, 

 and setae are disposed along the inner margin at fairly regular 

 intervals. These also occur on the fifth joint, which is the longest. 



The mandibles, maxillae, and maxillipedes very closely resemble 

 those of A. jJolaris. The epignath of the maxillipede is narrower 

 distally, and thus becomes more conical. 



Thoracic appendages. The first almost exactly resembles that of 

 A. polaris. The three following are also similar, but practically 

 devoid of spines ; the spines of A. polaris are represented by very 

 inconspicuous tubercles. The last three limbs bear one or two blunt 

 spines on the coxa and basis only and the ischium to the propodos 

 bear a row of small curved spines along the inner margin. 



Pleopods. The first pair are large and stout, forming a pro- 

 tecting shield to the remainder. Those which serve the branchial 

 function are less clavate than in A. polaris, and the basipodite bears 

 seven slender teeth as against five stouter ones. 



Five specimens of this species were taken among large numbers 

 of A. polaris off Cape Adare. 



Arcturus franklini. 



Specific character. A stout spine near the antero-lateral margin 

 of the cephalon, and six long slender spines on the second and third 

 thoracic segments. 



Cephalon of normal contour, with two stout spines between the 

 eyes, and directed slightly forwards, and a stout pair near the antero- 

 lateral angle. 



Thorax, first three segments with six long slender spines, two 

 dorsal, two dorso-lateral, and two epimeral. These spines are best 

 developed on the second and third segments, where they are particu- 

 larly prominent ; posterior segments of the thorax with numerous 

 small spines, for the most part situated laterally. 



Pleon, first three segments with a row of rather small spines 

 across the dorsum, and the last of the three having a very stout 

 lateral spine. The terminal segment bears numerous small spines 



