Prof. J. Miiller on the Structure of the Echinoderms. 253 



impressions appear like rounded dikes with closely-set trans- 

 verse or ziojzag insections, which appear to correspond in posi- 

 tion with the covering plates between the pinnulse. 



On making a transverse section of the hands, the involution 

 of the sides of the arms is observable. In a longitudinal section 

 perpendicular to the calyx, we observe not merely the interior of 

 the calyx and the above-mentioned overarching of the peripheral 

 portion of the cavity of the calyx, but also the ventral perisoma 

 above the calyx, which, passing from the hands, lies above the 

 overarching portion, and stretches like a line over the middle of 

 the calyx. The delicate pinnulse or marginal plates of the series 

 of joints of the hands are continued on to the ventral surface of 

 the calyx, and in sections may be traced to the middle, where in 

 all probability the mouth w^as situated. 



The composition of the stem is at present unknown. 



Among the numerous Crinoids of Gothland described and 

 figured by Hisinger in the ' Lethsea Suecica/ we look in vain for 

 any figure of reticulated arms, though there are not a few among 

 them whose arms have not been preserved. It is difficult to 

 conceive that among the many remains of Crinoids which he saw, 

 there should have been nothing appertaining to the reticulated 

 Crinoid ; and in fact there is a figure, not of the reticulated hands, 

 but of the calyx and the first joints, which would appear to do 

 so. It is his Cyathocrinics pulcher, " calycis articulis hexagonis 

 margine striatis, manibus circiter 35, brevibus linearibus, puncto 

 medio profundo, angulo recto infractis." Leth. Suec. Suppl. ii. 

 tab. 39. fig. 5. It would be impossible to conclude that this is 

 our Crinoid from the figure of the pieces of the calyx, which is 

 probably imperfect ; and the marginal striae figured upon them 

 are equally in disagreement with it. For in the Crinoid with re- 

 ticulated arms, the margin of the pieces of the calyx at the edges 

 by which they are in contact is in some parts excavated, and in 

 some entire, without the external surface of the pieces of the calyx 

 themselves being insected or striated. What however strongly 

 suggests that this is our Crinoid, is the figure of the lowermost 

 joints of the arms which are still attached to the calyx, and ex- 

 tend from without inwards as far as in the Crinoid with reticu- 

 lated arms, and possess the canal in the same situation and the 

 excavation upon the volar side. Hisinger has taken these joints 

 with their bare articular surfaces for short linear hands inflexed 

 at a right angle. The median deep point, which he speaks of, 

 is the nutritive canal which makes its appearance upon the arti- 

 cular surface of the joints. It is very difficult to make out 

 Hisinger's figure, and it would be quite impossible without a 

 knowledge of that internal structure of the joints peculiar to the 

 Crinoid with reticulated arms. The object there figured is 



