134 



Euapta tobagoensis n. sp. 



Tobago, B. W. I. IV.1916. 7 specimens. 



The specimens at hand measure 20 — 50 cm in length, and 

 their colour is brownish-grey with five dark-brown stripes, one in 

 each ambulacrum. The body-wall is thin and dry to the touch, 

 and not thick and slimy as in lappa. The specimens have all 15 

 tentacles, each supplied with 20 — 25 pairs of digits, united by a 

 web. On the oral disk there are eye-spots. The calcareous ring 

 (Fig. 9. 3) is bright green and there are no processes on its anterior 

 margin. The radial pieces are perforated for the nerves, and on 

 the exterior side of the ring there are distinct muscular impressions. 

 A cartilaginous ring is wanting. There are numerous polian vesicles 

 and one to two large madreporic canals. The gonads are branched 

 and the intestine has a large loop. On the mesenteries there are 

 ciliated funnels of the common size and shape. 



The anchors (Fig. 10. 7) measure ca. 380 ^ in length by ca. 

 220 [jl in width. The stock is branched and on the vertex there 

 are minute knobs. The anchor-plates (Fig. 10. 8-12) measure ca. 

 260 fi in length by 170 fi in width. The shape of the anchor- 

 plates is very variable, but the most common is that of the plate 

 figured, with two side-holes of equal size. The side-holes are often 

 wanting and then the bridge (as seen Fig. 10. 10-11) is formed as 

 a ring fastened to the posterior part of the articular end. There are 

 numerous intermediate stages between the plates with the two 

 equally large side-holes and the plates with the ring-shaped bridge 

 and no side-holes. Fig. 10. 9 shows the articular end of a plate 

 (several plates of that shape are found) which differs from the 

 normal plates in having the bridge fastened to the sides of the 

 large hole (the articular hole) in the articular end. The holes in 

 the anterior end of the anchor-plates are dented, and instead of 

 the second row of knobs, which is common in Opheodesoma, there 

 is a more or less complete, ring-shaped edge. 



The miliary granules are rosettes which are found all over the 

 skin and in the tentacles. In the oral disk and in the tentacles 

 there are curved rods, with a distinctly rough surface. The rods 

 in the tentacles (Fig. 8. 8) measure 130 — 200 fi in length and 

 have the ends bushy-branched. The rods in the oral disk (Fig. 8. 9) 



