REPORT ON THE CRINOIDEA. 97 
but he was unable to satisfy himself upon this point. The Naples variety of Antedon 
rosacea, upon which he worked, is about the worst type that could have been chosen 
for delicate observations of this kind, the quantity and character of the pigment- 
granules which the lip contains almost totally obscuring the other tissues. 
This pigment-substance is altogether different from the yellow and brown pigment 
masses so common in all Echinoderms. It is apparently related to the calcareous 
spicules which are so abundant in the under part of the perisome and in the intervisceral 
connective tissue. When these have been removed by acid their outlines are seen 
to be well defined by streaks of pigment-granules, which appear black by transmitted, 
‘and yellowish-white by reflected, light. They are especially abundant in the lip, and 
in some individuals almost entirely conceal the blood-vaseular plexus which it contains ;! 
while in specimens from other localities, and in Antedon eschrichti, it is scarcely developed 
at all, and I have found no difficulty in tracing the connection of the plexiform gland 
with the oral rmg. This is very evident in all the other Comatule, including Antedon, 
Actinometra, and Promachocrinus, which I have examined, as well as in Pentacrinus 
(PE EVI fis: 35Pl, DXi). 
The branching tubules depending from the oral ring which much resemble the visceral 
blood-vessels, .open into a dense plexus of more glandular looking tubules that is 
supported by connective tissue, and extends right round the lip (Pl. LVIL. figs. 1, 3, 4; 
Pl. LIX. fig. 5; Pl. LX. figs. 1, 2, 4—lp). 
It is connected with (1) the ventral branches of the plexiform gland (Pl. LVII. 
fig. 3, av); (2) with the genital vessels of the rays (Pl. LX. figs. 1, 2, gv); and (3) with 
some of the intervisceral vessels (Pl. LVII. figs. 1, 3, 4; Pl. LX. figs. 2,3, 5,7b; Pl. LXIL). 
These last form an extensive network over the coiled digestive tube, and are also directly 
connected with the plexiform gland (Pl. LVII. figs. 2,5; Pl. LVIIL. fig. 6, 7b). This 
labial plexus is most abundantly developed beneath the south and south-east portions of 
the peristome, 7.e., in the neighbourhood of the left posterior ambulacrum. It lies 
between the hind-gut forming the last coil of the digestive tube, and that part of the 
capacious fore-gut which lies between the two lateral ambulacra of the right side. It is 
always pretty sharply defined from the surrounding connective tissue, and is usually a some- 
what prominent object in a well-stained section which is examined with the naked eye ora 
simple lens. This is partly owing to the relatively thick walls of its component tubules, and 
partly to the delicacy of the connective tissue holding them together. Its relations are easily 
made out by the study of series of tranverse and longitudinal sections through the disk. 
It is not very specially developed beneath the origins of the anterior and antero- 
lateral ambulacra, the plexiform genital vessels of which may be traced into it; though 
it is somewhat denser on the left (east) than on the right side, where it is connected 
1 [ have found the same equally impracticable pigment in the disk of Actinometra pectinata from Singapore, and also 
in some individuals of Actinometra parvicirra from Bohol, although others from the same locality are totally devoid of it. 
(ZOOL, CHALL, EXP,—PART X¥XX11.—1884.) hls 
