342 ZOOLOGY. 



terest. Ten distinct geuera bave been diflferentiated and are represented 

 by seventeen known species. These have all been obtained in the deep sea, 

 at great depths. They exhibit extraordinary proportions and develoi^- 

 ment of the ambulacral appendages, and their siugnlarities have given 

 rise to some remarkable generic names, as Delma (a fright), Oneiro- 

 j)hanta (a vision), Ilyodemon (ooze spirit), and Irpa and Kolga (both 

 names derived from the ]!^orse mythology). " One group is very gelati- 

 nous, and of a rich purjjle color ; others are gelatinous, gray, and semi- 

 transparent ; while another series, and among these the most fantastic 

 of the whole, are yellowish, and have a crustaceous test, with a thick 

 laj'er of calcareous plates, often running out into strangely shaped pro- 

 cesses. A peculiar little group from the Antarctic Sea are little more 

 than a gelatinous membrane, covering an enormously distended intes- 

 tine, filled with diatom ooze." It is evident that the type is quite char- 

 acteristic of the abyssal fauna, for in most hauls of the dredge made in 

 very great dejJths forms are brought up in considerable number. 



SYSTEM OF STAR-FISHES. 



Mr. C. Viguier has investigated the comparative anatomy of the skel- 

 eton of star-fishes, and in connection therewith has applied the data 

 gained to the revision of the system.* He first recognizes two primary 

 groups, to which he gives (with doubtful propriety) the name of sub- 

 classes, and then divides these sub-classes into families, characterized 

 in the main by modifications of the frame work, as well as by the char- 

 acter of the odontophore, teeth, and pedicillaria. 



The first sub-class includes the typical star-fishes and related types, 

 as the Asteriadie, Heliasteridte, and Brisingidoe, which have, as common 

 characters, the mouth of the ambulacral type; i)edicilaria pedunculate, 

 and straight or claw shaj)ed, and the ambulacra generally in four rows. 

 The second sub-class is richest in representatives, and these have a 

 mouth of the adambulacral type, the pedicellaria sessile and valvular, 

 and the ambulacra are always biserial. Seven families are distin- 

 guished by the names Ecliinasieridic. Linclciadw, Goniasteridcv, Asterini- 

 dw, I'teraateridw, Astropectlnidw, and Archastcridct'. 



A GENERALIZED STAR-FISH. 



A form of star-fish (using the word in its broadest sense) has been 

 found in the sea about Madagascar, which is remarkable for certain of 

 its characters, for although in truth an ophiuroid, it exhibits some fea- 

 tures approximating it to the asteroids. According to the describer (Mr. 

 W. Percy Sladen),* indeed, the characters of Asteroidea and Ophiu- 

 roidea are combined in singular manner. The disk is enlarged and peu- 



* Viguier (C). Anatomie compardo tlu squelette ties Stell^rides, in Archives Zool. ex- 

 perim., t. vii, pp. 32-250. 



* Sladen (W. P.). On the Structure of Asthrophiura., a new and aberrant genus of 

 Ecbinodermata. Ann. Mag. Nat. Hist. (5,) vol. iv, pp. 401-415, pi. 20. 



