A treatise on zoology . some species of Astropeden the marginal ossicles are bordered byfringes of small spines, which A. Agassiz has compared to the fascicles of 252 THE STELLEROIDEA Spatangoids (see p. 319). In Ctenodiscus the grooves between the marginalossicles are bordered by bands of lamellae forming the simplest type ofcribriform organs. In the rest of the Porcellanasteridae these organs areconfined to a few special plates. In some species of this family theanus opens on tlie summit of a small tube. It rises from the abactinalsurface of the starfish, and lias been accordingly co
A treatise on zoology . some species of Astropeden the marginal ossicles are bordered byfringes of small spines, which A. Agassiz has compared to the fascicles of 252 THE STELLEROIDEA Spatangoids (see p. 319). In Ctenodiscus the grooves between the marginalossicles are bordered by bands of lamellae forming the simplest type ofcribriform organs. In the rest of the Porcellanasteridae these organs areconfined to a few special plates. In some species of this family theanus opens on tlie summit of a small tube. It rises from the abactinalsurface of the starfish, and lias been accordingly compared to the stemof Crinoids, an homology which is quite inadmissible. Family 7. AsTRorECXiNiDAE. Phanerozonia with opposite ambula-cral plates and paxilliform abactinal plates. Super-ambulacral plates arepresent, and the adambulacral plates are compressed. There is no anus,and pedicellariae are rarely present. The compressed adambulacral platesand the presence of a series of super-ambulacral plates, which occur inside. Fi<;. VIir. Porcellanaster caentleus. Abactinal surface sliowin;, cribiiforiu or^ans and anal tube. the arms above the ambulacrals, are the two most striking features ofthe Astropectinidae. The position of the super-ambulacral plates issliown in Fig. VII. There are two sub - families and nine 1. AsTiioiMOCTiNiNAE, incUuling tliose mcmbors of the familyin wliicli the adambulacral plates touch the infero-marginal platesalong th(! ray. The marginal and atlanibulacral plates do not corrospimdin length or number. (Jenera — A!<froprrtf)i^ Schul/e ; JUitlniJiiasttr^Danielssen and Koren ; Crcispiffaster, Slad. ; Dipsacaster, Alcock ; (syn. Lfpfoptifrhaster, Smith), (Fig. IX.) ; Moriasfn; , andPiiilaster, Sladen. Sub-Family 2. Luidiinae. Astropectinidae with arow of small plates separating the adambulacral and infero-marginalplates, (kliera—Antrelbi, Per. ; LuiiUn, Forbes ; Plntnsterias, Oray. Family 8. Pentaooxaht
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