294 CATALOGUE OF THE BLASTOIDEA. 



(PL XVII. fig. 14) represents the best we have been able to procure. Seven hydro- 

 spires are visible on one side of the ambulacrum, and eight on the other. 



Localities and Horizon. Bolland, Lancashire ; Clitheroe, Lancashire (Presented 

 by Mr. J. Eofe, F.G.S.) ; [County Dublin, as 0. prcelongus, Baily] : Carboniferous 

 Limestone. [Miller mentions Weston-super-Mare, Somersetshire, Black Rock, 

 Avon Section, Bristol, and Mitchell-Dean, Gloucestershire.] Tournay, Belgium 

 (as 0. Water// ousi anus, de Kon. & le Hon sp.) : Upper Carboniferous Shale. 



Order I RRE GU L ARES, E. & C, 1886. 



Definition. Unstalked Blastoids in which one ambulacrum and the corresponding 

 radial are different from their fellows. 



Remarks. We have established this Order to include three very remarkable genera 

 of Blastoids, our knowledge of which is far from being as complete as we could wish. 

 The best known of these is the Eleutherocrinus of Shumard and Yandell l , two species 

 of which occur in the Devonian Rocks of America (PL XIX. figs. 2-6). Some ten 

 years after it was first described, its differences from the other Blastoids were 

 recognized by Haeckel 2 , who gave expression to them in the following manner. He 

 divided the Class into two Orders, and in the first of these, which he called Elaea- 

 crina, he placed the three genera Pentremites, Codaster, and Elwacrinus, with the 

 following remark : " Abgesehen von dem excentrischen After, ist die Grundform fast 

 regelmassig pentactinot, nicht amphipleurisch." The second order, Eleutherocrina, 

 included but the single genus Eleutherocrinus, which differs from the, three types 

 already mentioned in " die sehr starke Differenzirung ihrer Antimeren und die 

 ausgezeichnete Pentamphipleuren Form." In a later work 3 , the name of the first 

 order is changed to Pentremitida, which are described as the " Regularly Budding 

 Lilies," while the Eleutherocrina are " Lilies budding on two sides," a description 

 which we cannot altogether understand. 



On the other hand, we have no hesitation in saying that the diagnosis of Eleuthero- 

 crinus which was published by Shumard and Yandell in 1856 is by far the best 

 account of a new generic type with which we are acquainted. The genus is a most 

 singular one in every way, and we have found with great interest that its chief 

 peculiarities are repeated in the curious little Astrocrinus of the British Carboniferous 

 Limestone (PL XX.), and also, though to a less extent, in the little known Pente- 

 phyllum (PL XVI. figs. 14-16). 



Eleutherocrinus, as seen from its anterior side (PL XIX. fig. 4), might readily be 

 mistaken for an ordinary regular Blastoid, such as Mesoblastus (PI. VI. fig. 12). But 



1 Troe. Acad. Nat. Sci. Philad. 1856, vol. viii. p. 54. 



2 GciHTclle Morphologic dcr Organismen (Berlin, 1866), Bd. ii. p. lxix. 



3 History of Creation (London, 1876), vol. ii. p. 166. 



