ANNOTATED LIST. 127 
Ophiocoma erinaceus. 
Ophiocoma erinaceus Miiller and Troschel. 1842. Sys. Ast., p. 98—H. L. Clark. 1915. Mem. M. C. Z., 25, 
p. 291, pl. 15, figs. 5, 6. 
Ophiocoma tartarea Lyman. 1861. Proc. Boston Soc. Nat. Hist., 8, p. 78. 
? Ophiocoma nigra, Michelin. 1863. Maillard’s Réunion, Annex A, p. 2. 
This perplexing form has a range nearly coincident with that of scolopendrina, and 
its true relation to that species has been the subject of much difference of opinion. Lyman 
regarded the two as distinct, saying that erinaceus can be distinguished by its large, central 
disk scales. Personally, I do not find this supposed difference in disk-scales a tangible and 
constant feature. De Loriol (1894) has given an excellent summary of the characters of 
erinaceus, which he considers quite distinct from scolopendrina. Koehler, on the other 
hand, as the result of his extended studies, concludes that there is no constant difference 
between the two forms. Matsumoto (1917) is decidedly of the same opinion and says 
emphatically: ‘“‘There is no doubt that O. scolopendrina, schenleinii, and erinaceus are 
conspecific.” Reef collecting at Mer has led me to a different conclusion, and my critical 
study of all the material in the Museum of Comparative Zodlogy leads me to believe that 
both erinaceus and schenleinii are at least incipient species. As I find little practical diffi- 
culty in separating mixed lots of Ophiocomas into these various species, I think it desirable 
for the present to retain the different names. 
The largest specimen of erinaceus which I have seen is 28 mm. across the disk and has 
arms 140 mm. long. In another specimen, 16 mm. in disk-diameter, the arms are only 
70 mm. long. The coloration shows little diversity, but it is interesting to note that some 
specimens from Mer have the tentacles red, as in riisei, whereas they are usually black. 
A specimen from Hilo also has red tentacles and the general color is red-brown, instead of 
black, with the arms distally banded with light and dark red-brown. This specimen has 
more granules than usual orally. A specimen from Ponape has 2 or 3 short radiating light 
lines on disk at base of each arm and the lower, basal arm-spines are light with a dark 
longitudinal stripe. 
At Mer we found erinaceus very common in the Pocillopora, Acropora, and Seria- 
topora zone, 600 to 1,200 feet from high-water mark. It lived among the coral branches 
and only occasionally was it to be found on the sand under rock fragments. It is a much 
more active species than scolopendrina, and when the coral in which an individual was 
sheltered was broken up, the Ophiocomas quickly sought concealment. The color in life 
is very black, but in young specimens the tips of the arms may be banded, and on the oral 
side of the arms transverse white lines are not infrequent distally, even in large specimens. 
As already mentioned, some individuals had the tentacles bright orange-red, and one of 
these is further remarkable for having the radial shields, though small, bare, and distinet— 
a very unusual condition for an Ophiocoma. 
Ophiocoma pica. 
Ophiocoma pica Miiller and Troschel. 1842. Sys. Ast., p. 101. 
Ophiocoma lineolata Miller and Troschel. 1842. Sys. Ast., p. 102. 
Ophiocoma sannio Lyman. 1861. Proc. Boston Soc. Nat. Hist., 8, p. 81. 
(Plate 13, Figure 8.) 
This is not only the handsomest, but it is the least variable member of the genus. 
The arms are always short and rather stout, seldom much over four times the disk-diameter 
and often only three and a half times. The largest specimen in the Museum of Compara- 
tive Zodlogy is 23 mm. across the disk and has arms 80 mm. long. The disk granulation is 
finer than in most Ophiocomas, but still evidently coarser than in brevipes. It extends only 
a short distance onto the oral surface. The arm-spines are 5 or 6 in each series proximally 
and seem quite crowded; distally there are but 4. There is little variation in form of the 
arm-plates and oral shields. The oral papille are usually only 3 or 4 on a side, but the 
