440 DR. P. II. CARPENTER ON 



remains as the side-plate, with a squarish hase and pointed top ; while the distal limb of 

 the fork becomes the rounded covering-plate (PI. L1I. figs. 6, 7). As in all the Penta- 

 crinidse, the two series end some little way before the extremity of the pinnule, the 

 ventral groove of which is thus left entirely unprotected. It is rare to find any indi- 

 viduals of Metacrinus some part of which does not exhibit irregularities of growth ; and 

 M . rottmdus is no exception to the rule, the seat of the irregularity in this case being 

 the basal ring. One of the basals is much wider than its fellows, and looks as if it were 

 divided into two unequal parts, one of which slightly overlaps the other. This may be 

 i\uti either to an anomalous mode of growth from the beginning, or else to fracture and 

 subsequent reparation. The point is not one of very great importance, but is only of 

 interest from the frequent occurrence of similar irregularities in Metacrinus and their 

 comparative absence in Pentacrinus, which seems, as it were, to be somewhat more crys- 

 tallized in the regularity of its characters. 



The fine specimen of Myzostoma cirripedmrn (PI. LII. fig. 19), which is described 

 further on by Prof, von Graff, was attached to this individual; while its cirri afforded 

 anchorage to those of a small Antedon. 



Dr. Doderlein informs me that it was attached to the tangles, and had the arms closed 

 in over the disk when it was first removed from the water, but that they opened out 

 after a time. Most of them eventually broke off at the syzygy in the third distichal 

 after the specimen bad been put into spirit. Its colour, however, has altered but little 

 in consequence. 



2. Metacrinus mperbus, sp. nov. (PI. LI. ; PL LII. figs. 8-12.) 



Dimensions. 



Length of stem to twenty-sixth node 30 centimetres. 



Diameter ?■?.-, millimetres. 



Longest cirrus, 68 joints 80 - 00 



Diameter of disk 30-01) 



Length of broken arm after suprapalmar axillary, 100 joints . 105*00 „ 



Length of first palmar pinnule, 27 joints 36"00 ,, 



„ „ pinnule after suprapalmar axillary, 22 joints . 18'00 „ 



Stem very robust, with a rounded pentangular outline and smooth flat sides. 9-11 

 internodal joints, with moderately crenulated edges. The angles of the nodal joint* 

 scarcely project at all, and the wide cirrus-sockets between them extend well up on to 

 the supranodals, though but very slightly on to the infranodals. The cirri increase in 

 size down to the seventeenth node, and then remain tolerably uniform. They consist of 

 about 05 stout, but short and wide joints. The intcrarticular pores disappear at the 

 eighteenth node. 



Basals prominent, and widely pentagonal, with downward extensions over the upper 

 stem-joints. Radials wide, usually four in number, with a syzygy in the second. 



The rays divide four times, and the outermost of each pair of the arms which are 

 borne by the suprapalmar axillary divides again, so that the number of arms must exceed 



