1876.] 



Biology of the ^Valorous' Cruise, 1875. 



225 



twelve segments in a total length of about 0*12 inch. On the other hand, 

 in the 1450 fathoms dredging (No. 12) are fragments T\hich appear to 

 belong to the same type, except that the small end of each segment is 

 elongated into a tubular neck ^Yhich intervenes between each segment and 

 its successor, so that the w^hole test would present the aspect of a tube 

 with egg-shaped enlargements at intervals. The length of a single flask- 

 shaped segment with its neck is sometimes as much as 0*16 inch. 



c. Another series, which 1 may distinguish as the " orthocerine," con- 

 sists of arenaceous tubes, sometimes attaining a length of 0-8 or even 

 0-9 inch, having an average diameter of about 0*1 inch ; they usually 

 vary but little in diameter from one end to the other, but are slightly 

 constricted at somewhat irregular intervals, so as to show an imperfect 

 division into about ten or twelve segments. When perfect, these tubes 

 are usually closed and rounded at one end, which encloses a globose or 

 ovoid chamber, commonly marlved off from the rest either by an external 

 constiiction or by an internal thickening of the wall. At the other ex- 

 tremity the tube, which is there often somewhat conical, has a circular 

 mouth; but the finish of this mouth, as of the entire tube, is not nearly 

 so perfect as in the types already described. The incomplete segmenta- 

 tion of each tube pretty obviously marks successive additions to its 

 length ; and these additions are far less uniform in length than they are 

 in transverse diameter; so that while the latter is pretty constant 

 throughout, the length of a segment may be much less than its breadth, 

 or may be as much as twice as great. — The special interest of this ortho- 

 cerine test, therefore, consists in its combination of inconstancy of detail 

 with great constancy of general form and proportion, and in the transi- 

 tional stage it presents between the monothalamous and the polythala- 

 mous types. For the whole cavity may in one sense be said to consist 

 of but a single chamber ; whilst in another it may be said to be com - 

 posed of a series of freely communicating chambers. And the component 

 sand-grains are much less firmly cemented together than they are in the 

 preceding types — some specimens approaching, in the looseness of their 

 aggregation, the Astrorhizce and the large polythalamous orthocerine 

 Lituolce of the 'Lightning' collection*, as also the monothalamous 

 Lituolce collected in the ' Porcupine' t, whose claim to relationship to the 

 preceding mainly consists in the possession of a sHghtly projecting 

 circular mouth, along the border of w-hich the sand-grains are united by 

 the ferruginous cement which is almost entirely wanting in the "test" 

 generally. 



The sarcodic contents of these Lituolce have the dark olive-green hue 

 ^^ hich I have previously noticed as prevalent among the large arenaceous 

 deep-sea Eoraminifera. But it is a curious circumstance that many of 

 the " orthocerine " tubes were found to be occupied by a large parasitic 



VOL. XXV. 



