73 



ten Asteriscus, som den ligner i dens pentagonale Form, 

 dens Bevæbning saavel paa den convexe Kyg som den 

 flade Bug med meget smaa stumpe eller spidse kalkag- 

 tige Børster eller Pigge, samt ved Skivens og Armenes 

 steilt nedadheldende og nedentil skarpe Rand uden syn- 

 lige Randplader. Ved at afskrabe Piggene bemærkedes 

 imidlertid, at Randens Skarphed kun er tilsyneladende 

 og har sin Grund deri, at Piggene ganske skjule de dor- 

 sale og den dorsale Del af de ventrale Randplader. Den 

 saaledes af 2 Rader Randplader dannede Rand bliver 

 derfor i Virkeligheden affladet og høi, samt kun lidt skarp 

 eller vinklet der, hvor den gaar over i Bugfladen. Da 

 der altsaa findes Randplader, saavel dorsale som ventrale, 

 hvilke begge bidrage til Dannelsen af den høie Rand, 

 kan vort Dyr ikke være en Asteriscus, men maa blive at 

 henføre til Slægten Goniaster Agassiz (Astrogonium M. T.) 

 eller Goniodiscus M. T. 



Kroppen er (se Fig. 24) pentagonal med kun yderst lidet 

 indbøiede Sider, Ryggen noget convex med en meget svag 

 rundagtig Fordybning i Midten af alle 5 Interradier, Armenes 

 Spids stumpt tilrundet, Randen (Pentagonens Sider) tem- 

 melig høi, og Bugen ganske flad. Dyrets Tvermaal fra 

 den ene til den anden ligeoverfor staaende Armspids ud- 

 gjør 11 Mm., deraf Skivens Radius 5 Mm. og Armens 

 Radius 6 Mm., Kroppens største Høide 2 l / 2 Mm? Krop- 

 pens af Randpladerne dannede Rand 1 1 / 2 Mm. høi. Farven 

 af det levende Dyr var meget bleg morgenrødlig; i Spi- 

 ritus bliver den hvid. 



De dorsale Bandplader (Fig. 25, g), i Antal 10 fra en 

 Armspids til den anden, ere noget bredere end lange, ovale 

 eller næsten rectangulære med tilrundede Hjørner, og om- 

 trent af lige Størrelse med Undtagelse af de yderste paa hver 

 Side, hvilke efterhaanden blive mindre imod Armspidsen, 

 Deres Overflade er noget convex og temmelig tæt besat 

 med kalkagtige Børster eller cylindriske, i Enden stumpt 

 tilrundede Pigge (a), alle omtrent af lige Størrelse. 



De ventrale Bandplader, ligeledes 10 i Tallet, ere 

 stillede, ikke lige under de dorsale, men hver af dem 

 under to af disse, altsaa alternerende med dem. De ere 

 af en mere rectangulær Form og en god Del bredere end 

 de dorsale, idet de nemlig ikke alene i Forening med 

 disse bidrage til at danne Kroppens 5 Siderande, men 

 ogsaa danner en Bræmme langs ad den flade Bugsides 

 Rand. Deres dorsale Halvdel (Fig. 25, h), som danner den 

 nedre Del af Kroppens Siderande, er noget convex og tæt 

 besat med de samme Slags Børster eller Smaapigge som 

 de, der bedække de dorsale Randplader. Disse Smaapigge 

 tiltage noget i Størrelse imod den ydre Rand, som er 

 garneret med en tæt Rad af 6 saadanne, hvilke næsten 

 ere halvt saa lange som Pladen, paa hvilken de sidde, og 

 rettede skraat udad og nedad og saaledes bidrage til at give 

 Randen Udseende af at være skarp. Den ventrale Halvdel 

 af disse Plader (Fig. 26, m), som danner en Vinkel med den 



a species of the genus Asteriscus, which it resembles in 

 its pentagonal form, its armature, as well on the convex 

 back as on the flat belly, in the shape of very small ob- 

 tuse or pointed calcareous bristles or spines, and also 

 in the margin of the disc and arms inclining steeply 

 downwards with a sharp edge below, and without visible 

 marginal plates. But on scraping off the spines, it was 

 observed that the sharpness of the edge is only apparent, 

 and is caused by the spines quite concealing the dorsal, 

 and the dorsal part of the ventral marginal plates. Thus 

 the edge formed by 2 rows of marginal plates becomes 

 in reality obtuse and high, and only a little sharp or 

 angular where it goes over into the ventral surface. As 

 therefore the marginal plates exist, as well ventral as 

 dorsal, which both concur in forming the high margin, 

 our animal cannot be an Asteriscus, but must be refer- 

 red to the genus Goniaster Agassiz (Astrogonium M. T.) 

 or Goniodiscus M. T. 



The body (see fig. 24) is pentagonal with only very 

 slightly incurved sides. The back is somewhat convex 

 with a very slight roundish hollow in the middle of all 

 the 5 interradial spaces, the points of the arms obtusely 

 rounded; the margin (sides of the pentagon) rather high, 

 and the belly quite flat. The transverse diameter of the 

 animal from the point of one arm to the opposite side 

 is 11 Mm. of which the radius of the disc 5 Mm. and 

 the radius of the arm 6 Mm. The greatest height of the 

 body 27 2 Mm.; the margin of the body formed by the 

 marginal plates l l / a Mm. high. The color of the living 

 animal is very pale pink; in spirit it becomes nearly 

 white. 



The dorsal marginal plates (ß.g. 25. g) 10 in number 

 from the point of one arm to another, are somewhat 

 broader they are long, oval or nearly rectangular with 

 rounded angles and about of the same size, excepting 

 the outer ones on each side, which gradually become 

 smaller towards the point of the arm. Their surface is 

 somewhat convex and rather closely covered with calca- 

 reous bristles or cylindrical spines (a) obtusely rounded 

 at the extremity and about of equal size. 



The ventral marginal plates, likewise 10 in number, 

 are placed not quite under the dorsal, but each under 

 two of the latter, thus alternating with them. They are 

 of a more rectangular form, and a good deal broader 

 than the dorsal; as they not only, in connexion with the 

 dorsal marginal plates, contribute to form the 5 lateral 

 margins of the body, but also form a rim along the margin 

 of the flat-ventral side. Their dorsal half (fig. 25, h), 

 which forms the lower part of the lateral margins of the 

 body, is somewhat convex and thickly covered with the 

 same sort of bristles or small spines as those which cover 

 the dorsal marginal plates. These small spines increase 

 a little in size towards the exterior margin, which is 

 garnished with a close row of 6 of them, all nearly half 

 as long as the plate wheron they are situated, and 

 directed obliquely outwards and downwards, thus contri- 

 buting to give the margin the appearance of being sharp. 



10 



