67 



føddernes, altsaa udgjør omtrent 75 paa hver Side 

 af Bugfuren (hos P. pulvillus kun 34—38 paa hver Side 

 af Bugfuren). Hver anden af dem (Fig. 9, d) er nemlig kor- 

 tere og strækker sig indad til en Sugefod af den ydre Rad 

 (a), hver anden er noget længere (c) (hos de 2 andre Arter 

 ere alle hinanden nærstaaende af samme Længde, medens 

 de som sædvanlig efterhaanden imod Armspidsen blive kor- 

 tere) og løber mellem 2 Sugefødder af den ydre Rad ind til 

 en Sugefod af den indre Rad (&), og saaledes bestandigt 

 afvexlende. Der er i de længere Tværfinner (Fig. 10, 11) 

 5 Pigge (c), hvilke indenfra udad tiltage noget i Længde ; i 

 de kortere (Fig. 13) er der ligeledes 5, men den inderste af 

 dem bliver pludselig meget liden, omtrent 3 Gange kortere 

 og tyndere end den nærmeste og er stillet udenfor eller paa 

 den aborale Side af denne, medens samtlige øvrige danne 

 en næsten lige Tværrad. Alle disse Pigge ere naaleformige, 

 temmelig stærke, tilspidsede i Enden og med deres tykkere 

 Basis bevægeligt indleddede paa en liden rund Knude, og 

 samtlige forbundne ved en mellem dem udspændt tynd 

 Hud, som over Enden af Piggene gaar ud i høit frem- 

 ragende eller temmelig lange fortykkede eller kjødede Lappe (d) 

 af tunge- eller lancetdannet Form, hvis Band er uregelmæs- 

 sigt bugtet og foldet. Den forbindende Hud fortsætter sig 

 i de ovenfor omtalte lave, liniedannede, udad paa Bræm- 

 men lige til dens Rand løbende parallele Hudfolder. Hos 

 P. pulvillus er der i Tværfinnerne (se Fig. 19), med Undta- 

 gelse af de nær ved Armens Spids staaende, almindelig 6 

 Pigge, sjeldnere inderst en meget liden syvende, af hvilke 

 den inderste (a) (eller naar der er 7 de 2 inderste) er kor- 

 test, den anden (eller tredie) er længst, de øvrige lidt kor- 

 tere, og den dem forbindende Hud er i Randen temmelig 

 stærkt bueformig indskaaren mellem Piggene, og disses En- 

 despids overrages kun lidet af Huden, som her er noget 

 fortykket og danner en tilrundet eller kort-tungeformig 

 Lap (d) for hver Pig. Hos P. militaris er der i Tværfinnerne 

 (Fig. 20) ligeledes almindelig 6 Pigge, af hvilke den inderste 

 (a) er mindst, de øvrige omtrent lige lange og den forbin- 

 dende Hud er svagt (mindre stærkt end hos P. pulvillus) 

 bueformig indskaaren mellem Piggene og overrager ikke 

 disse, saa at de ikke fortykkede Lappe over Piggenes 

 Ende blive triangulært tilspidsede (.d). 



Den inderst ved Munden staaende Tvær finne (Fig. 14, m) 

 er, ligesom hos P. pulvillus, forvoxen med den tilsvarende 

 fra den nærmest ved beliggende Bugfure til en eneste, som 

 derved faar Form af en Vifte og danner en af de 5 Mund- 

 vinkler. Denne Vifte (o) bestaar af 10 ved Hud forbundne 

 Pigge, nemlig 5 (i ét Tilfælde fandtes i den ene 6) i hver 

 af de med hinanden forvoxne Tværfinner, hvilke Pigge 

 danne en bueformig Rad paa den inderste eller imod 

 Munden vendte Rand af de 2 inderste Adambulacral- 

 plader, paa hvilke de sidde. Disse Plader ere ligesom hos 

 de 2 andre Arter mere udviklede end de øvrige Adam- 



responds to that of the water-feet and amounts therefore 

 to about 75 on each side of the ventral furrow (in the 

 P. pulvillus only 34 — 38 on each side of the ventral 

 furrow). Every alternate one of them (fig. 9, d) is shorter, 

 and extends inwards to a water-foot of the outer series 

 (a)-, and every other somewhat longer (c) (in the 2 other 

 species they are situated close together and of the same 

 length becoming only gradually shorter towards the points 

 of the arms) running between 2 suction-feet of the ex- 

 terior series inwards to a suction foot of the interior series 

 (b)\ and so on continually alternating. There are in 

 the longer transverse fins (fig. 10, 11) 5 spines (c), which 

 from within outwards increase somewhat in length; in 

 the shorter fins (fig. 13) there are also 5; but the inner- 

 most of these becomes suddenly very small, about V 3 of 

 the length of that next to it, and thinner, being also 

 situated somewhat more in front or on the ab oral side, 

 while all the other spines form a nearly straight trans- 

 verse row. All these spines are needle-shaped, rather 

 strong and pointed at the extremity, with their thicker 

 base movably articulated on a small round tubercle; and 

 all of them connected by a thin membrane, stretched 

 between them, terminating over the ends of the spines in 

 a high prominent or rather long swollen or fleshy tongue- 

 shaped or lancet-shaped lobe (d) the margin of which is 

 irregularly bent and folded. The connecting membrane is 

 continued in the previously mentioned low linear parallel 

 skin folds running out on the border even to its edge. 

 In P. pulvillus there are in the transverse fins (see üg. 

 19), with exception of those near the points of the arms, 

 usually 6 spines, (rarely innermost a very small seventh) 

 of which the innermost (a), or where there are 7 the 2 

 innermost) shortest; the second (or third) longest, and 

 the others a little shorter; and the connecting membrane 

 is at the margin rather strongly incurved between the 

 spines; the terminal points being only a little overlapped 

 by the skin, which is here somewhat thickened, and forms 

 a rounded or shortly-tongue-shaped lobe (d) for each 

 spine. In the P. militaris there are in the transverse 

 fins (fig. 20) likewise usually G spines, of which the in- 

 nermost (a) is smallest; the others about equally long, 

 and the connecting membrane is slightly (less strongly 

 than in the P. pulvillus) incurved between the spines and 

 does not overlap them; so that the lobes over the extre- 

 mities of the spines are not thickened, but terminate in 

 points (d). 



The transverse fin situated innermost near the mouth 

 (fig. 14, m) is as in P. pulvillus connate with the corres- 

 ponding fin from the nearest ventral ambulacrum, so as 

 to form one fin in the form of a fan, and occupies one 

 of the 5 bucal angles. This fan (o) consists of 10 spines 

 connected by a membrane; namely 5 (in one case there 

 were found 6 in one) in each of the connate transverse 

 fins, the spines of which form a curved row from the in- 

 nermost border (that nearest the mouth) of the 2 interior 

 adambulacral plates on which they are situated. These 

 plates are, as in the 2 other species, more developed 



9* 



