PROF. OWEN ON A NEW SPECIES OF EUPLECTELLA. 119 



up chiefly of portions of a coarse irregular siliceous sponge, which appears to be foreign to 

 the proper body of the Eitplectella, and includes some shells and other marine calcareous 

 bodies. Some of the fine long fibrils, emerging from the mass, converge, as they are reflected 

 back (fig. 2), and, after a few graceful bondings, again diverge into separate wavy locks of 

 the most delicate hairs, having a silken or silvery lustre {h, h, figs. 1 & 2). The whole of 

 this beautiful elongated filamentous medium of attachment of the Euplectella may be 

 compared to a lock or tuft of the haii" which Poets feign to have adorned the head of 

 the Syren or Mermaid. 



The number of the longitudinal fibres at the base of the cone in Euplectella Asper- 

 gillum is sixty, in Euplectella Cucumer it is fifty-three : their number at the apex in 

 Euplectella Aspergillum is thirty, in Euplectella Cucumer it is thu'ty-fivc. I would not, 

 however, be understood as confiding in these particular numbers being constant and cha- 

 racteristic of the species. The fibres of the reticiilate cap consist of converging and of 

 connecting or transverse kinds : many of the former are continued from the confluence 

 of two of the longitudinal fibres of the cyluidi-oid, where they become bent at nearly right 

 angles after leaving the connecting marginal band to form the cap : such fibres show a 

 thickness proportionate to the additional material entering into their composition. The 

 degree of irregularity in the converging and connecting fibres forming the reticulate cap 

 is like that in Euplectella Aspergillum* . The superficial fine oblique series of fibres, with 

 the superadded multii-adiate spicula, terminate abruptly at the marginal rim in Euplec- 

 tella Cucumer, just as the ridges of the cylinder terminate in Euplectella Aspergillwm. 



Dr. A. Farre notes, as the result of Ms study of the structure of the Euplectella Cucumer, 

 that " the obUque lines are not formed out of one continuous line of fibre for each side, 

 wound round and roimd, which is the idea of a spiral, but they consist of a double series of 

 ellipses, placed at definite distances, which intersect each other at right angles, or nearly so. 

 These form perfect ellipses only towai'ds the centre of the specimen, for at either end they 

 are necessarily interrupted. In these oblique fibres there occur the same confluence of two 

 contiguous lines, in some places, and divergence or bifurcation of simple ones in others, 

 as happen in the longitudinal series, and evidently with the same object of adapting their 

 arrangement to the increasing or diminishing diameter of the cy Under. With regard to 

 the relative positions of the longitudinal, transverse and oblique fibres, I find that these 

 lie in several alternate series. First a bundle of about half-a-dozen longitudinal close- 

 lying fibres. These run straight from end to end of the cylinder. 



except where they bifurcate or combine. Then the looser bundles of oblique fibres 

 decussate with the longitudinal ones, the fibres separating to pass over, under, and 

 between them, and at the same time intersecting the fibres of the opposite oblique series 

 in a similar way. 



* Compare PI. 13, Trans. Zool. Soc. vol. iii. % J, w-ith fig. Z in PI. XXI. 



