BEACHIONID^. 117 



and thick muscular tube, very transparent, covered with minute and close wrinkles, full 

 of muscles, which admit of rapid protrusion and retraction, and of motion in all direc- 

 tions, with amazing flexibility (so that I have actually seen it tied in what, for the 

 moment, looked like a knot!). The toes, — so small and apparently feeble, — have con- 

 siderable power of grasping. They are sometimes used as a pivot on which the animal 

 revolves. The mutual relations of the sexes are very distinct ; as I have shown in detail 

 in my Memoir "On the Dioecious Character &c." {Phil. Trans. 1856). The female 

 carries the excluded eggs attached to her body till they are hatched. 



The distinction of the species rests mainly on the number, dimensions, and relations 

 of the spines. Yet recent observations on B. ixila throw doubt on the validity of such 

 characters. — P.H.G.] 



B. p.\LA, Ehrenhcrg. 



(PI. XXVII. fig. 3 ; and PL XXVIII. fig. 3.) 



Brachiomis pala . . . . Ehrenberg, Die 7?^/MS. 1838, p. 511, Taf. Ixiii. fig. 1. 



„ amphiccros . . „ Die Infus. 1838, p. 511, Taf. Ixiii. fig. 2. 



„ polyacanthtts . . Cohn, Sicb. u. Kiill. Zcits. Bd. xii. 1863, Taf. xxii. fig. 4. 



„ amphiceros . . Plate, /cjjatsc/i. ^i;j7s./.A''ai!(r. 1885, p. 65, Taf. ii. figs. 22-24. 



SP. CH. Lorica thin, smooth, transparent ; with four, long, sharp, occipital spines. 



B. pala has a colourless, smooth and transparent lorica, armed with four long spines 

 in front, but unarmed and rounded off behind. The lorica is flexible, and generally 

 dragged-in a little on either side, roimd the attachments of the long dorsal muscles. 

 The opening for the foot is a mere slit, through a pap-like protuberance at the end of 

 the lorica ; and its sides can be brought close together when the foot is withdrawn. The 

 animal's internal organization is very like that of B. ruhens, which has already been so 

 fully described in Chapter I. that, beyond a reference to PI. A, vol. i., and PI. XXVII. 

 fig. 3, only a few points rec[uire notice. The mastax is very large ; and so are the trans- 

 parent vesicles which are seated on it on the ventr^^J side, and may possibly be salivary 

 glands. By transmitted light they show only two curved lines (their outer boundmg 

 walls) rising from the mastax to the head. The gastric glands are stalked, as in B. 

 ruhens, but the stalks are generally hidden behind the broad triangular ends of the glands.' 

 The vascular system is very conspicuous, and the five tags on each side can be readily 

 found. I once obtained an admirable view of the top of a vibratile tag, which was 

 pointing up the microscope. It was not at all like that of Euchlanis dilatata given by 

 Dr. Plate, and taken from the same point of view. Dr. Plate figures the summit of the 

 tag as an oval with pointed ends. I found that of the lowest tag of B. pala to be a thin 

 straight edge, Uke that of a chisel. If there be an aperture there, it must be extremely 

 narrow. As the animal moved, the tag turned too, so as to present also the two charac- 

 teristic appearances given in PI. XIII. fig. Sb. 



Along with the undoubted specimens of B. pala were a good many of what appeared 

 to be Ehrenberg's B. amphiceros, with two short thorn-like spines on the lumbar 

 regions, and two others still smaller, one on each pap-like protuberance by the foot 

 (fig. 8t'). Ehreuberg says that B. amphiccros differs from B. pala in its smaller size, m 

 having no coronal styles, in having four sharp posterior spines on the lorica, in lacking 

 side muscles in fi'ont, and in having four vibratile tags instead of three. Moreover he 

 says that he could not find a dorsal antenna. Now I carefully examined these speci- 

 mens with four posterior spines, and fomid them to be of the same .size as B. pala, with 

 styles on the corona, with side muscles in front, and possessing a large dorsal antenna. 

 In fact they were the exact counterparts of pala. I may add, too, that both those which 

 had, and those which had not posterior spines, showed, mider favourable circumstances, 

 five vibratile tags on each side. Nor is this all : for I found some specimens with two 



' The lower ends of these glands are tied to threads, which are attached to the lorica just above the 

 heads of the lateral antennie, and at their other extremities to the stomach. Mr. Gosse discovered 

 and drew this arrangement, as well as the lateral antenna; themselves, in 1850. 



