KONGL. SV. VET. AKADEMIEXS HANDL. BAND 19. N:n 7. 43 



as good as any given since. ^) He Avas also acquainted with another sort of pedicels, namely 

 those belonging to the frontal ambulacrum of Echinocardium flavescens, and possessed 

 figures of these, made by his brother and draughtsman C. F. Muller. These figures, 

 however, were not published till long afterwards, in 1789, by Abildgaard ■) who was 

 well aware of the distinctness of the frontal pedicels from those surrounding the mouth. 

 It will seem that 0. F. Muller had regarded both as being of one and the same sort, 

 when he made use of their structure, very happily after all though, as an essential 

 character distinguishing his genus Spatangus: ^ttentaculis peniciUatis^\ from the genus 

 Echinus: ^Hentaculis shnplicibus-n. ^) This is indeed the first important step towards a 

 rational dismemberment of the great Linna>an genus Echinus, and 0. F. Muller is to 

 be considered as the real author of the natural genus Spatangus since adopted by 

 Lamarck. The name, borrowed from Aristoteles, had been in use with the Museo- 

 graphers of the pre-Linnajan era for certain artificial divisions. 



It is, however, mainly to the account given by Johannes Muller'') of the various 

 kinds of pedicels occurring in the Echinoidea, that we have to turn for the principal 

 source of information respecting these important organs. After having remarked that 

 not all the regular Echinoidea ai'e homoiopodous, that is, have the whole of their pedicels 

 terminating in. a sucking-disk, as Duvernoy had presumed, but that certain genera, as 

 Echinocidaris, Astropyga, Diadema, and Colobocentrus, have the dorsal pedicels simply 

 pointed and flattened, and, the last named genus excepted, plaited on the sides, thus 

 suggesting a respiratory function, he proceeds to give the following general description 

 of these organs, as they occur in the Spatangida^. In this group four different kinds 

 of pedicels may be distinguished: 1) simple locomotive pedicels with truncated or 

 rounded tops, destitute of sucking-disks; 2) locomotive pedicels provided Avith a terminal 

 circular sucking-disk, either crenulated at the margin and strengthened inwardly Avitli 

 radiating calcified laminae, or divided into radiating processes containing calcareous 

 rods or lamels; 3) tactual, penicillate pedicels, ending in expanded brushes of club- 

 shaped filaments, inwardly sustained by calcareous rods; 4) branchial pedicels, ambulacral 

 gills, having the shape of triangular leaflets with plaited sides. In one and the same 

 ambulacrum there may be found two or even three of these kinds succeeding one 

 another, between the peristome and the dorsal pole. Wherever a fasciole is present, one 

 kind of pedicels is peculiar to the area it circumscribes. In the genus Spatangus Joh. 

 Muller recognises three kinds: tactual, locomotive and branchial. The circum-oral 

 pedicels of all the five ambulacra are tactual and penicillate, the rest of the ventral ones 

 simple and locomotive. Within the sub-anal fasciole there stand on either side three 



') Zoologia; Danicfe Prodromus, 1776, p. XXIX. — Zoologia Daiiica, I, t. VI, fig. 5, 1777; latin letter- 

 press, in 8:0, 1779, I, p. 11; in fol., 1788, p. 5; clanish letterpress, in foL, 1781, p. 19. The 

 erratum, Zool. Dan. Prodr. p. XXIX: "ano infero", is here corrected to "auo laterali". 



-) Zool. Dan. Ill, p. 17, t. XCI, fig. 4. «Terminantur disco radiato, radiis clavatis, alternis longioribus. 

 Tentacula vero, qu* poros ad circumferentiam oris trauseunt fasciculo penicillate filamentis capitatis 

 coniposito terrainanturo, Abildg. 



3) Zool. Dan. Prodr., p. XXIX. 



^) Ueber den Bau der Echinodermen. Abhandl. d. K. Akademie d. Wissensch. in Berlin, 1854, sep. p. 26, 

 pi. III. 



