4 Ech, 
ECHINODERMATA. 
On the apical area of Echinoids, see Agassiz (1a). 
Perrier (20) thinks that the so-called heart is glandular in nature, and 
proposes to call it the ovoid gland ; he recognizes the nervous nature of 
the chambered organ, on which the Carpenters have insisted, an opinion 
to which no continental naturalist has yet publicly recorded his adhesion. 
Romanes (21) adduces evidence which he believes to prove the existence 
of an olfactory sense in Starfishes. 
Selenka (22) describes the phenomena of cleavage and the characters 
of the mesenchj'm in Synapta digitata, Echinids, and Ophiurids, the meso- 
derm, nervous system, and mouth and anus of Cucumaria planci. Differ- 
ences in the mode of cleavage are not to be regarded as having any 
phylogenetic value. The mesoblast arises from two primitive cells of the 
mesenchym, and from diverticula of the archenteron. Their develop- 
mental history points to the origin of Echinoderms from worm-like 
ancestors. 
In his studies on the histology of the Echinodermata , Hamann (10, 11) 
has chiefly investigated Holothurians ; some observations are also made 
on the nervous system of Asterids. While the former have the connec- 
tive tissue well developed and the tegumentary epithelium thin, the 
reverse of these conditions is fcund in the latter. The nervous system 
of Starfishes calls to mind that of the Ccelenterata , and the simplest type 
of optic organ in any group of the Animal Kingdom is found in them. 
Semon (23) has investigated the microscopic as well as the macroscopic 
characters of the nervous system of Holothurians ; the latter are espe- 
cially difficult of investigation, and care must be taken as to the methods 
employed. 
Mackintosh (17) has investigated the minute structure of the spines of 
Arbaciidce , and of some Echinometridce and Echinidce, and makes some 
corrections and additions to his earlier notices of the Diadematidcc and 
Echinothuriidce. 
ECHINOIDEA. 
Among others, de Loriol (14) has notes on — 
j Rhabdocidaris gigantea, imperialis , dubia. 
Echinothrix desori. 
Echinus versiculatus , Liitken, is not a synonym of Echinus angulosus. 
Echinus robillardi , sp. n. 
Pseudoboletia Indiana and P. maculata have been confused by Bell 
[who, Ann. N. II. (5) xiii. p. 108, accepts the statement, but points out 
how and why he followed A. Agassiz]. 
Echinostrephus molaris. 
Stomopneustes variolaris. 
Echinoneus cyclostomus , E. abnormalis , sp. n. 
Maretia alta. 
Bell (2) disputes the validity of the characters by which Peronella has 
been distinguished from Laganum , and points out that the extent of the 
development of the partitions appears to depend on growth and age. 
On the differences between Rotula rumphi and R. dentata , see 
de Rochebrune, N. Arch. Mus. (2) iv. p. 328. 
