hot,othuriid;e, bchinid-®. 
Ech . 5 
Both genera are also worked out anatomically ; they are apneumonous, 
have an intestinal channel of the usual S-shape, but only two latero- 
vcntral ambulacral canals, answering to and communicating with the 
latero- ventral series of feet ; the dorsal feet are entirely excluded from 
any communication with the aquiferous system. In Elpidia, the ambu- 
lacral canals are divided into chambers, each chamber corresponding to 
one foot. In this genus also auditory vesicles were observed, with 
otoliths, one near the origin of each of the four nerve-trunks (the dorsal 
and the latero- ventral) and one (or two) where the nerve-branches spring 
from the latero- ventral trunks. In both genera the chalk-ring has quite 
a peculiar character, it consists of five, radially placed, chalk-stars, with 
eight long branches, forming, by certain branches being placed alongside 
of each other, a regular pentagon, &c. The end of the madreporic 
tube is attached, not floating freely, &c. 
A renewed examination of Rhopalodina lageniformis has shown (14, 4) 
that it is only an abnormal Holothurian, and that the order “ Diplosto- 
midea ” must bo abolished. The ambulacra originating from the month 
are continued directly, at the bottom of the dilated portion of the flask- 
shaped body, in those terminating at the vent ; the transformation of an 
ordinary sea-cucumber into Rhopalodina might be effected through the 
shortening and absolute suppression of the dorsal inter-radial area, in such 
a manner that mouth and vent were brought into immediate contact and 
juxtaposition. 
Cucumaria marioni, Marenzeller (IG), p. 117, pi. v. fig. 1 (Marseilles) • 
Holotkwia helleri, id. affinis, Heller), 1. c. p. 119 ; Thyone raphanus^ 
K. & D., from Marseilles, ihid. pi. v. fig. 2. 
RCTTlNrD;R. 
Ludwig (14, 3) has made the discovery, that in several (probably all) 
Spatangidoi the plates of the odd interambulacrum, nearest to the peri- 
proct, are connected with each other by a strip of true muscular tissue, 
situated in a longitudinal furrow corresponding to the median line of 
union of the two series of plates. The want of a muscular connection 
between the plates of the pcrisome (not to be confounded with its plia- 
bility in Perischcchinidm, C^V?anWa?, jE'c7«mo/7mrwV7(B, &c.), therefore can no 
longer be upheld as an absolute character of the Echinidm. This obser- 
vation also explains the fractured state of the corresponding part of the 
shell so often found in fossil Spatangidce. 
Notes by G. McIntosh on the microscopical structure of spines of 
EchinidWj and on the teeth, sphgeridia, gills, spicules, &c., are shortly 
recorded in Q. J. Micr. Sci. xvii. pp. 104-106, 191, 192, 195, 303, & 463 
Fredi^riq’s notes on the anatomy and physiology of Ecliinidce [cf. Zool. 
Rec. xiii.] are translated in Ann. N. H. (4) xix. pp. 195-198. A note 
by Giebel on Echinothrix desori\ Z. ges. Naturw. (3) ii. pp. 319 & 
320. 
Duncan (4) has demonstrated the existence of sphaeridia in a recent 
Salenia (S. profundi, sp. n.), near the peristome, on the ambulacra ; also the 
existence of pedicellarioe on the test and apical disk ; with further descrip- 
