"ENDEAVOUR" SCIENTIFIC KESULTS. 168 



pinnae generally equal from half to three-fourths the length of a 

 hydrotheca, and those on the stem are still further separated, 

 while in Allman's figure they are mostly close together. The 

 hydrothecae according to Allman are more tumid below than in 

 our specimens, and the hydrocaulns is much more contracted 

 between the pairs. The chitinous prolongations downward of 

 the hydrofcheca- walls ("stalk-marks" of Leviusen), which are 

 very pronounced in the present form, are not indicated in 

 Allman's figure. 



In regard to the form of the aperture my specimens differ very 

 materially from Allman's account. H. labrona is described as 

 having a thin membranous inoperculate lip, trumpet-shaped, 

 circular, and at right angles to the terminal part of the 

 hydrotheca (in other words at an angle of 45 to the axis of the 

 hydrocaulns), and liable to be readily detached at a suture in the 

 neck of the hydrotheca, which runs parallel with the border. 

 In H. distans the aperture is nearly vertical, indeed in so far as 

 it diverges from the vertical it does so in the opposite direction 

 to Allman's figure, that is to say the upper side of the hydro- 

 theca projects outward even further than the lower, so that the 

 border slopes downward and slightly inward. The lip is thin, 

 but not circular nor trumpet-shaped, and it does not appear at 

 all liable to detachment. It may be -noted however that the 

 delicacy of its perisarc is such that it shrivels up when placed in 

 a dense medium, so that it is scarcely possible to find a 

 perfect example in a balsam-mounted specimen unless special 

 precautions are taken. There is no definite line of demarcation 

 between the lip and the rest of the hydrotheca, the perisarc 

 simply thins away to the margin. The aperture is widest from 

 side to side ; in the ordinary aspect of the polypidom the two 

 slight lateral angles are scarcely noticeable, but in side view they 

 are more distinct. There is an abcauline opercular flap, which 

 is most commonly seen in a vertical position, just within the 

 aperture, but is also frequently found in the position in which 

 Allman represents the suture. I have not found such a suture 

 in any instance, and I think it possible that Allman may have 

 misinterpreted the operculum, which, seen edge-wise, often 

 appears as a sharply-defined line. 



The whole border structure is practically the same as in 

 Sertularia tnba, to which species the present form shows a 

 singularly close resemblance in the form and arrangement of the 

 hydrothecas, as well as in the ramification, though differing in its 

 much larger proportions throughout, as well as in the presence 

 of the pouch-like appendages of the hydrotheca^ which AHman 

 considers undoubtedly sarcothecae. I have not been able to 

 satisfy myself as to the true character of these structures, and I 

 find great difficulty in the way of accepting Allman's view. In 



