226 



Dr. J. Gwyn Jeffreys on the 



[June 15^ 



Protozoon of tlie Gregarina type. The most careful examiuation has failed 

 to detect in this any higher organization than that of ordinary Gregarince ; 

 and its parasitic character may be inferred from the fact that I often 

 foimd it coexisting in the same tube with the ordinary sarcodic body of 

 the Lituolce, which was then more or less reduced in bulk, indicating that 

 the latter had been partially preyed on by the former. Moreover, I 

 found a precisely similar body coiled up in the midst of a mass of sand 

 that occupied the interior of a large detached and partly broken spherical 

 segment of a nodosarine." 



d. Another series of " orthocerine " Lituolce is of great interest as 

 conducting us towards what seems at first sight an entirely distinct t3'-pe, 

 the Rliabdammina of Sars. These are straight tubular cylindrical rods, 

 nearly uniform in diameter, and distinguished from the preceding by 

 their extreme slenderness. Some of them are nearly an inch in length, 

 while their diameter neyer exceeds 0'03 inch, being often not half that 

 amount. The larger of these specimens presented themselves in great 

 abundance in the 410 fathoms dredging (No. 6, Davis Strait) ; the 

 smaller and less numerous examples in the 1750 fathoms dredging 

 (Xo. 9). Sometimes they are nearly uniform in size from end to 

 end ; in other cases there are constrictions at irregular intervals, 

 forming an imperfect segmentation ; while sometimes the tube nar- 

 rows for part of its length, and then enlarges agam. The sand-grains, 

 usually rather coarse, of which these tubes are composed are very firmly 

 united by ferruginous cement ; and the non-segmented rods bear so exact 

 a resemblance to those which form the extensions of the triradiate 

 Rhahdammina (Sars), that they might easily be supposed to be detached 

 arms of that very curious form*. Li fact, when we met with similar 

 rods in dredgings containing also large numbers of Rhahdammince, this 

 was the light in which my colleague was accustomed to regard them. A 

 careful examination of the varietal forms of Rhahdammina^ howcA'er, had 

 led me to the conclusion that the typical triradiate form might graduate 

 into a single long rod; for when, as often happens, one of the three rays 

 is imperfectly developed, the others are not only longer than usual, but 

 diverge at an angle greater than 120°, this divergence increasing in propor- 

 tion to the suppression of a third ray, until it reaches 170°, so that the 

 two rays come so nearly into the same straight line, that a single very 

 long straight rod may be considered as the representati^-e of two of the 

 three rays of the typical triradiate Rhahdammina. And I used to enforce 

 this view by a . comparison of the large number of single straight rods 

 which often came up in one dredging, with the small number of tri- 

 radiate centra from which they could be supposed to be detached — the 

 former being often siv or eight times as numerous as the other, whilst 

 they ought not to have exceeded three times. Now in the two ' Yalorous ' 

 dredgings which furnished these straight rods in the greatest abundance 

 ^ Proceedings of the Eoyal Society, xvii. p. 172. 



