4 Ech. 
ECHINODEKMATA. 
organs, which appear to be gills, and to replace in function the external 
branchiae of most other regular Echinoidea. Ludwig (Z. wiss. Zool. 
xxxiv'. p, 82) makes very similar observations, in complete ignorance of 
those of Stewart (Zool. Anz. iii. p. 162), and extends the observation to 
the Diadcmatldce. Special armed pedicellariae are described as existing in 
the Cidaridce. 
Bell’s observations (2 & 4) take as their starting-point the “ Revision of 
the Echini by Alex. Agassiz, the definitions in which are critically ex- 
amined ; in (2), he gives tables of measurements to exhibit the characters 
of the paired anterior and posterior ambulacra, and shows that from them 
no specific difference can be formulated as existing between Brissus uni- 
color and B. carinatus ; the same beiug true of the angles formed by the 
fasciole, he comes to the conclusion that the species should be united. On 
p. 255, ho gives in a condensed form the characters otMeoma, Brissus, and 
Metcdia, and points out that the first of these exhibits the most simple 
arrangement. In (4), he deals in a somewhat similar way with the genus 
Tripneustes (rejecting the name Hipponoe) : he figures the different parts 
of the dentary apparatus, and points out the gradation in characters which 
are to be detected in the three species of the genus. 
Bell (3) examines the arrangement of the anal plates in EcJiino- 
cidaris, and shows that the number four may be reduced or exceeded ; 
out of 31 specimens examined, 9 had cither more or less than four plates. 
The organs noticed by Noll (Zool. Anz. ii. p. 405) in some Echinoidea 
are stated by Ludwig (/. c. p. 455) to be the well-known “ Mund-fuss- 
chen.’' 
Haacke (Zool. Anz. ii. p. 641) describes an abnormal arrangement of 
the intestine in Asteracanthion ruhens. 
Barrois (J. de I’Anat. Phys. xv. p. 1) describes the development of 
Asteriscus verraculatus. From the gastrula, W'hich is of the primitive 
type, a tri-lobod larva is developed, the side lobes of w'hich fall away. 
At one point in its life, the young exhibits great asymmetry, and has the 
mouth eccentric in position. The ambulacral joints of the arms are said 
to increase in number in just the same way as the zonites of Annelids, 
and he would extend the remark from the Astcroidca to the Echinoidea. 
Viguicr’s elaborate memoir (26) is of interest, as a serious attempt 
to come to a rational classification of the Asteroidca, Without entering, 
in any way, into the question of how far ho has been successful, a short 
notice of some of his results may bo given. The class Stelleridce con- 
sists of two subclasses, (1) “ Asteries ambulacraires,” (2) “ A. adambula- 
craires.” These names apply to the two types on which the mouth-parts 
are developed in the subclasses. In the former, the paired ambulacral 
pieces are said to extend further into the mouth, while the adambulacral 
pieces are truncated, and the odontophore (why the azygous intermediate 
piece is so named, it is hard to say) is massive and without apophyses. 
In the second subclass, the adambulacral pieces are never completely 
truncated, and the odontophore is nearly always provided with apophyses. 
The pedicellariae are pedunculated in the former, and the ambulacral 
suckers are ordinarily arranged in four rows ; in the second, the pedicel- 
laiim are sessile, and the ambulacral suckers almost always sessile. 
