MICROCYPHUS. 323 



These two species are from southeastern Australia, the home of M. zigzag, while 

 maculatus ranges from Mauritius, where it appears to be common, to Japan and 

 Samoa. It is a curious fact that adults of maculatus seem to be rare. Of three 

 hundred and forty-three specimens in the M. C. Z. collection, three hundred and 

 forty are less than 16 mm. h. d., one is 16 mm., one is 26.5 mm. and one is 30 

 mm. The two last are simply bare tests; the larger is the one figured in the 

 "Revision." So far as can be judged these large ones are not different from 

 the small ones except in such points as would be involved in their larger size. 

 In coloring, tuberculation, and pitting of the test, maculatus appears to be very 

 variable, but the coloring of the spines is fairly constant. For this reason, 

 it cannot be doubted that the species mentioned by Mortensen, from Tor, on 

 the Red Sea, is perfectly distinct, and may be called cricacanthus {KpUos = a 

 circle + aKavOa = a thorn, supine) . It is unlikely it will prove to be Rousseaui, as 

 the latter is most probably the adult of maculatus. As for Anthechinus roseus 

 A. Ag., a reexamination of the type-specimen, now in the M. C. Z. collection, 

 leaves no room for question that it is maculatus. The test of young maculatus 

 is usually somewhat greenish or yellowish, with the bare abactinal spaces, rang- 

 ing from almost white to pure deep rose-color. Of the large specimens, one has 

 the bare spaces dull rose and the other very dark gray. Among our three 

 hundred and forty small specimens, no less than four are more or less per- 

 fectly tetramerous. 



The five species of Microcyphus may be distinguished as follows : — 



Test low, vertical diameter .50-.70 h. d.; interambulacral plates few, 6-10 in each col- 

 umn; ambulacral plates nearly or quite twice as numerous; poriferous areas 

 broad; pore-pairs distinctly biserial actinally in large specimens, the inner series, 

 of pore-pairs only, the outer, of pore-pairs alternating with small tubercles. 

 Spines green, sometimes with light tips, and rarely with one or two distal bands . maculatus. 



Spines red-brown, banded with 2-4 lighter rings cricacanthus. 



Test high, vertical diameter .75-.90 h. d.; interambulacral plates 10-18 in each column; 

 ambulacrals only a little more numerous; poriferous areas narrow, without 

 tubercles and not biserial actinally. 

 Spines light, greenish at base, white at tip, broadly encircled by a band of red; bare 



interambulacral spaces broad and very hght colored antiulatus. 



Spines not banded. 



Bare interambulacral spaces narrow and dark colored (j-ellowish brown in 



young, almost black in adults) ; spines deep red zigzag. 



Bare interambulacral spaces narrow, rose-red; spines pale reddish .... compsus 



