384 DISCOVERY REPORTS 



an adult animal of about 50 mm. diameter. The differences in the form of the tentacular 

 pouches in both cases are obvious. In the younger specimen the tentacular pouches are 

 distally very broad. Where the long thin lappets arise their outline is curved inward. 

 In the older stages the tentacular pouches are much more elongated, more slender and 

 distally less expanded, and the incurvation at the origins of the lappet canals is less 

 pronounced. In both cases the pigment of the tentacular pouches reaches to the bases 

 of the tentacles surrounding them. In the older specimens the subtentacular 

 POUCHES on the subumbrella near the insertion of the tentacles are indicated in Fig. 8 b 

 with fine dots. The ends of these pouches reach far into the lappets and are also 

 deeply pigmented. This makes it rather difficult to understand the anatomy of the 

 lappet zone and of the insertion of tentacles. A thorough study of the anatomy of 

 these parts seems to be very necessary, but this is beyond the scope of the present 

 report. In both figures the circular muscle is figured as being partially cut off. 



The COLOUR is in all specimens nearly the same, the smaller ones generally a little 

 less dark than the older ones. All are a very dark, deep purple-brown, and much more 

 intensely and brilliantly coloured than in the somewhat faded specimens figured by 

 Vanhoeffen. On the exumbrella all grooves or deeper lying parts are deeply pigmented, 

 especially the coronal furrow, or show at least traces of pigment, as, for instance, the 

 radial furrows on the central disc. In most specimens the subumbrella too is more or 

 less covered with a thick layer of the dark purple brown pigment, which has become 

 partially separated, or hangs here and there in small patches from the surface. Often the 

 ring muscle is wholly covered with pigment, or stained in many places with reddish 

 brown spots, as is the case with the gonads. The gastro-vascular system is very distinctly 

 visible, by its own strong pigmentation, through the more superficial thin pigment 

 stratum. The circular muscle and gonads are, if not covered with pigment, of a yellowish 

 colour, and the muscle sometimes has a greenish yellow hue and is more or less iridescent. 

 The stomach, if not covered by dark pigment, has a greyish blue tint. Generally 

 speaking the pigment in the specimens-of A. chuni is better preserved than in those of 

 A. wyvillei, and it seems to be darker and more resistant. 



The GONADS develop rather late. Specimens smaller than 30 mm. diameter have no 

 gonads. In specimens of 50-60 mm. diameter the gonads are strongly folded and form 

 a nearly complete ring, while in smaller ones they are in the form of eight perfect sacs 

 which lie separated from each other at equal distances, or constitute four pairs. Often 

 it was possible to distinguish the eggs in the sacs with the naked eye. If not mature, the 

 gonads are easily overlooked, because they are covered with the thick layer of dark 

 pigment. 



Geographical distribution (see Fig . 9) . The catches of the ' Discovery ' have greatly 

 enlarged our knowledge of the distribution oiAtolla chuni. Up till now only three indi- 

 viduals from two localities in the neighbourhood of Bouvet Island were known. In 

 the broad band between 30 and 55° S the 'Discovery' found no less than forty-three 

 specimens. Most individuals have been taken between the west of the Cape of Good 



