2 Ccel 
C(ELENTERATA. 
Heliopora is not a polyactinarian Anthozoon, but an Alcyonarian. It 
will form (with the fossil genera Polytremacis and Heliolites) a family 
Ilelioporidce, thus, characterized : — “A compact corallum, composed of 
a fibro-crystalline calcareous tissue, and consisting of an abundant 
tubular coenenchyma ; calicles having an ^irregular number of latei*al 
ridges resembling septa, closed below, as are also the ccenenchymal 
tubes, by a succession of entire transverse partitions (tabulae) ; polypes 
completely retractile, with tentacles when in retraction introverted ; 
mouths of the sacs lining the ccenenchymal tubes closed with a layer of 
soft tissue, but communicating with one another and with the calicular 
cavities by a system of superficial transverse canals.” The “ coenen- 
chymal tubes” surrounding the calicles of the true polypes, are evi- 
dently rudimentary “ zooids,” analogous to those of the Pennatulidce and 
Sarcophyton (of which a species js studied for comparison), but closed 
up, without mouth, stomach, mesenteria, sexual organs, or mesenteric 
filaments. The structure of the polypes is that of the Alcyonaria : eight 
tentacles and mesenteria, mesenteric filaments, &c. The bilateral 
arrangement of the retractor muscles of the mesenteries agrees with 
that of the Pennatulidce and Sarcophyton, and, as in these, a “ dorsal ” and 
a “ventral” compartment may be distinguished. The hard parts of the 
corallum are not formed by the fusion of spicules, as in Tuhipora, &c. 
Among the fossil “ Tahulata/* Chcctetes, Favosites, Michelinia, A Iveolites^ 
and Syrlngopora are probably also Alcyonarians. The Actinozoon 
nature of Pocillopora, on the other hand, is confirmed. 
Korotneff (5) has studied, without knowing anything of the researches 
of Duncan and Ludwig [Zool. E,ec. xii. p. 557], the enigmatical mar- 
ginal bodies of Actinia mesembryanthemum. Though his interpretations 
and results agree best with those of the last-named author, these are 
however, somewhat modified. The said organs are special sense organs, 
most resembling organs of taste, but not of a very highly specialized type. 
Externally, is a stratum of triangular “ cnidocils ” with elliptical bases, 
Eotteken’s “rod-like” bodies and “lenses,” and then a layer of long 
Cylindrical nematocysts, each abutting against a “ cnidocil,” while other 
cnidocils are connected with fibrils from the third or fibrillary layer, 
consisting of fibrils, traversing and connecting fusiform cells, probably 
of nervous nature. The fourth layer is the “ elastic membrane ” (hya- 
line lamella ” in Hydroids), Rotteken’s muscular stratum ; the fifth the 
endoderm. The tentacles of Lucernaria and Corynactis afford similar 
structures. 
Eisen's monograph (3) of a littoral Renilla from the Californian Coast 
is of value, because of its being based upon the examination of fresh 
and living specimens. Kolliker’s statements on the structure of these 
Alcyonaria are confirmed. The polypites, which are, as ordinarily, only 
placed upon the superior surface of the reniform disc, are of two kinds : 
the true polypites (provided with tentacula of the usual conformation 
and with organs of generation), retractile into their “ zooecia,” which, 
placed side by side, and only separated by the walls of the sarcosoma, 
constitute the whole polyparium ; and the small “ zooids” (without 
reproductive organs and without tentacula, but with a short stomach and 
