1 1 1 



much larger and stiffer than Pj or P s , recurved and horn-like, the 

 component segments with produced and spinous distal ends .... Cenometra 

 b 2 10 arms; size small ; at least the outer cirrus segments nearly or quite 

 as long as broad, bearing dorsally a serrate transverse ridge (sometimes 

 two, a proximal and a distal) or long spines 



c 1 P x shorter, smaller and weaker than P 3 ; P 3 , and usually also P 3 , 

 elongated, enlarged and stiffened, with the distal edges of the 

 segments produced into spinous overlapping borders, or with the 

 distal portion of the prismatic angles produced into rounded or 

 pointed processes 



d l 30 or more cirrus segments of which only the basal bear transverse 



ridges these after the proximal fourth of the cirrus transforming 



into very long dorsal spines; P 3 has at most 12 segments . . Cotylometra 



d 2 25 or fewer (usually about 20) cirrus segments, of which all but 



the terminal bear transverse ridges ; P 3 has at least 15, and 



usually about 20, segments Oligometra 



c 3 Pj the longest and stoutest pinnule on the arm 



d 1 the third-fifth segments of the genital pinnules more or less 

 expanded laterally to protect the genital glands; a single median 

 transverse ridge on the cirrus segments 

 e 1 P p though longer and stouter than P 3 , not exceptionally so; 



median transverse ridge on the cirrus segments of moderate height Austrometra ') 

 e 2 Pj much stouter than P 3 , and so enlarged basally as to cause 

 the second brachial to appear like an axillary ; median ridge 



on the cirrus segments very high Analcidometra 



d 2 110 expansion of the genital pinnules; the cirrus segments bear 



two transverse ridges, a proximal and a distal Oligometrides 



P„ absent 



b 1 more than 10 arms 



c 1 Pj as long as, and similar to, P 3 ; IIBr series commonly 4 (3 -|~4);_ 



outer cirrus segments with a low dorsal transverse ridge .... Petasometra 

 c 2 Pj shorter than P 2 ; all the division series always 2 ; outer cirrus 

 segments somewhat shorter than the proximal, bearing paired or 

 tripled dorsal spines which on the terminal become resolved into a 

 single median spine, or a median carination 



d 1 Pj much smaller, weaker and more slender than the enlarged 

 and stiffened P 2 ; 10 — 30 arms; 21 — 30 cirrus segments; outer 

 cirrus segments with paired or tripled dorsal spines, which become 

 a single median spine terminally Cyllometra 



1) Genotype Oligometra thttidis H. L. Clark, 1909; this genus is only known from southeastem Australia. 



