ZOOLOGY. 485 



Granatohlastidcv, with two genera; (5) Codasteridcv, with four genera, 

 two of which belong to the special subfamily Phicnoschismidw, and the 

 other two to another named Cri/ptoschismidw. 



The second order of blastoidea is named Irregulares, and is restricted 

 to "unstalked blastoids, in which one ambulacrum, and the corre- 

 sponding radial are different from theii fellows," and the " base usually 

 unsjnnmetrical.'' This group includes only one family, long ago called 

 AstrocrinidcE^ but amended by Messrs. Etheridge and Carpenter, and 

 made to include three genera. 



According to Messrs. Etheridge and Carpenter, the true Mastoids do 

 not appear previous to the Upper Silurian period, and they appear to 

 have become extinct long before the close of the Carboniferous, no traces 

 of blastoids from the Lower Carboniferous (or calciferous sandstone 

 series), much less from any of the marine bands of the coal measures, 

 being recognized. 



All the known blastoids of " the Upper Silurian period are confined 

 to American strata, and represent the families Troostoblastidse and 

 Codasteridse." 



In the Devonian period "all the families are represented. The Si- 

 lurian Troostoblastidae, however, do not appear in the American De- 

 vonian rocks; but they are well represented in Europe, although the 

 Devonian blastoids generally are slightly more numerous both iu genera 

 and species iu America than in Europe. Iu Europe the great center of 

 blastoid life in Devonian times appears to have been in the north of 

 Spain, whilst iu the British isles there is but the scantiest evidence of 

 their presence in the rocks of that period." (Etheridge and Carj^enter, 

 ojp. cit.; An. and Mag. Nat. Hist. (5), xviii, pp. 412-417.) 



Asterioids. 



Organization of star-Jishes. — In the course of investigation of a new 

 incubating star-fish from Cape Horu. to which the uiime Asterias hyadesi 

 has been given. Prof. Edmond Perrier has described a peculiar organ, 

 and deduced certain conclusions iu respect to the taxonomy of the echi- 

 noderms : 



" On the wall of the sacciform canal which surrounds the hydrophoral 

 tube there is attached a probb'matic organ, which is prolonged beyond 

 the sacciform canal, in such a way as to form two organs connected with 

 the intestine, and giving off two lateral branches, which are in direct 

 relation with the genital glands. This problematic organ, which has 

 lately been called the chromatogeuous organ by Hamann, has in young 

 Asterias hyadesi the form of a lateral conical prolongation of the peri- 

 toneal membrane of the digestive sac, and it contains a large number of 

 vitelline bodies identical with those of the wall of the sac. The lobes of 

 its surface are continuous with the trabeculte which form the living basis 

 of the skeleton of the star fish, and it dilates at its external surface into 

 membranes, which envelop the hydrophoral tube. This collateral organ 



