ECHINOIDEA. SPATANGOIDA. 



247 



brissus A. Ag., Caribbean ; Aceste W. Thorn., 600 to 2,600 fathoms ; 

 Aerope W. Thorn., 800 to 1,750 fathoms ; Palaeotropus Loven, 82 to 375 

 fms. ; Homolampas A. Ag., 32 to 2,475 fms. ; 

 Argopatagus A. Ag., 800 fms. 



Fam. 3. Leskiidae. Test thin, ovoid. Api- 

 cal system with three basals fused into one ; 

 two large genital pores upon conical promin- 

 ences. Peristome in front, pentagonal, with 

 five angular buccal plates. A peripetalous 

 fascicle. Palaeostoma Loven, China. 



Fam. 4. Pourtalesiidae. Elongated and 

 Holothurian-like in appearance. Test thin, 

 transparent. Mouth terminal in front. Anus 

 behind, above the posterior projecting rostrum 

 if that is present, or terminal on the actinal 

 surface. Apical system variable, compact or 

 disjunct. Peristomial margin also variable : 

 in some species Loven's law is carried out, in 

 others it is not. Ambulacra not petaloid. 

 With four or three genital openings. Plates 

 for the most part with single pores ; tube- 

 feet homoiopodous. Is the living representa- 

 tive of the Cretaceous genus In/ulaster 

 Hag. Atlantic and Pacific, 345 to 3,000 fms. 

 Pourtalesia A. Ag., Spatagocystis A. Ag., Echinocrepis A. Ag. 



FIG. 176. Apical region of Pour- 

 talesia jeffreysi (after Loven, 

 from Delage). gtx genital 

 opening ; mdp madreporite. 



Class HOLOTHUROIDEA.* Sea-cucumbers. 



Elongated, worm-like Echinoderms with a dermo-muscular 

 body wall containing small isolated calcareous bodies. With con- 

 tractile tentacles surrounding the mouth and containing prolonga- 

 tions of the water-vascular system. The apical system of plates 

 is not developed at any stage of life, and the water -vascular pore 



* J. Miiller, Ueb. Synapta digitata u. ub. die Erzeugung von Schnecken in 

 Holothurien, Berlin, 1852. G. F. Jaeger, De Holothuriis. Diss. Inaug. 

 Zurich, 1833. De Quatrefages, Mem. sur la Synapte de Duvernoy, Ann. 

 Sci. Nat. (2), 17, 1842. A. Baur, Beit. z. Naturgesch. d; Synapta digitata, 

 Dresden, 1864, and Jena, 1865. Semper, Holothurien, Reisen in Archipel 

 der Phillipinen, II. 1, 1868. H. Ludwig, " The Holothuroidea," Mem. of 

 the Museum ofComp. Zoology Harvard College, vol. 17, 1894. Id. "Holo- 

 thuroidea " in Bronn's Klassen und Ordnungen des Thierreichs, Bd. 2, Abt. 

 3, 1889-1892. Theel, Hj., "Report on the Holothuroidea," Challenger 

 Reports, Pt. 1, in vol. 4, 1882, and Pt. 2, in vol. 14, 1886. Id., " Report 

 on the Holothuroidea," Bull. Mus. Com. Zool. Harvard College, 13, 1886. 

 R. Perrier, Holothuries, Exped. Sc. Travailleur et Talisman, 2, 1902, 

 p. 273. A. Kowalevsky, Beit. z. Ent. d. Holothurien, Petersbourg, 1867. 

 R. Semon, Entwick. d. Synapta, Jena. Zeitschrift, 22, 1888, p. 175. H. 

 Ludwig, Zur Entwick. der Holothurien (Cucumaria planci), Sitzber. k. 

 Preuss. Acad. d. Wiss. Berlin, 1891. E. Herouard, Recherches sur les 

 Holothuries des cotes de France, Arch. Zool. Exp. (2), 7, 1889, p. 555, and 

 Holothuries provenant des campagnes de la " Princesse Alice," Res. 

 camp. sc. Monaco, Fasc. 21, 1902. Romanes and Ewart, Observations on 

 the locomotor system of Echinodermata, Phil. Trans., 1882, p. 829. 



