io5 



d* arm bases j^erfectly smooth; synarthrial tubercles, if present, narrow 

 and conical ; P 4 much shorter than P 3 ; elongated proximal pinnules 

 more slender, with the component segments more elongated, beyond 

 the seventh to the tenth twice as long as broad, and distally three 

 times as long as broad 



e 1 narrow and conical synarthrial tubercles present; P 3 2 mm. to 

 3 mm. longer than P 2 ; proximal pinnules stift" and wiry; habit 



robust; 45 — 47 arms (sou thern J apan) gotoi 



e 3 no synarthrial tubercles; P 3 0.5 mm. to 1.5 mm. longer than P 2 ; 

 proximal pinnules delicate; habit slender and delicate; less than 

 42 arms 



f 1 34 — 42 arms 1 10 mm. to 120 mm. long; cirri 30 mm. long with 

 29 — 35 (usually 33) segments; P., and P 3 with 31 — 34 segments; 

 division series and arms as far as the third brachial thickly 

 sprinkled with minute white dots (e ast coast of India) . ciliata 

 f 2 29 arms about 85 mm. long; cirri 15 mm. to 18 mm. long 

 with 23 — 29 segments; P 2 and P., with 22 — 25 segments; division 

 series and arm bases without white dots (southeastern 

 Africa and Madagascar) afra 



1. Dichroiuetra tenuicirra A. H. Clark. 



A. H. Clark. Ann. and Mag. Nat. Hist., series S, vol. 10, 1912, p. 34. 



Stat. 318. 6°36'.5S., ii4°S5'.5E. 88 Metres. 1 Ex". 

 Stat. 320. ó°5'S., U4°7'E. 82 Metres. 25 Ex. 



The centrodorsal is low hemispherical with very sloping sides ; the dorsal pole is slightly 

 convex, flat, or very slightly concave, 1.5 mm. to 2.5 mm. in diameter; the cirrus sockets are 

 arranged in two, or in two and a partial third, irregular and crowded marginal rows. 



The cirri are XIX — XXVIII, 25 — 28 (usually 26), 20 mm. to 25 mm. long, slender 

 and delicate ; the tenth-twelfth (usually the tvvelfth) is a more or less marked transition segment ; 

 the first segment is very short, the second twice as broad as long, the third slightly broader 

 than long, the fourth from half again to twice as lone as the median 

 diameter, the fifth from two to two and one half times as long as 



broad; the following to the ninth, tenth or eleventh are similar; the 



remainder are slightly shorter, about half again as long as broad ; Fig. 5. 



the tenth-twelfth and following bear prominent triangular median Lateral view of a cirrus fiom 



01 ° a specimen of Dichrometra tenui- 



spines ; after one or two segments these spines occupy about half of «>ra from stat. 320. x 2. (Cour- 



. , . , • 11 tesy of the U. S. National Museum). 



the mid-dorsal line ; the antenor (distal) margin stands out vertically, 



and is from one half to one third as long as the recumbent side; the hypothenuse, from the 

 apex of the spine to the proximal base, is straight, but its proximal end may be marked by 

 a slight tubercle, or the hypothenuse may be slightly concave, leading from the distal spine 



S1BOGA-EXPED1TIE Xl.Il/. 14 



