438 PERCY SLADEN TRUST EXPEDITION 



The genitalia ($) do not call for any particular comment. The oviducal glands are 

 very small, the ovary is symmetrical and the oviducal apertures are simple and placed 

 very near the anus. The genital artery enters the capsule of the ovary in an anterior 

 position between the two ducts which are separate at their origin. 



The hrancMce (fig. 5 h, c) have their laminse diagonally plicate. 



2. Polypus arborescens Hoyle. (Plate 66, fig. 3.) Kept. Pearl Oyster Fisheries of 

 Ceylon, (Koy. Soc.) Pt. ii. p. 189, 1904. 



One example, $, from Cargados, 30 fms. (1411). 



One example, $, from saine (1403) (dark variety?). 



These are unmistakable examples of Hoyle's species. 



Distribution previously known : Ceylon ; Zanzibar ; Pacific Ocean. 



The mandibles (cf. fig. 3 b). 



The radula. The first lateral tooth is rather deep, the second singularly long and 

 accompanied by a rather slender third lateral. The median tooth exhibits a very deep 

 basal notch. 



The internal organs. In the example No. 1411 the ovary was so much enlarged and 

 reflected posteriorly that it covered the whole of the branchial complex and practically 

 obscured the gills themselves from view. Apparently by reason of this development of the 

 ovary (no doubt attained by numerous other species at the time of sexual maturity) the 

 following somewhat anomalous condition of the branchial complex and surrounding organs 

 is to be noted : 



(i) the gills lie at a very low level, 



(ii) the heart is displaced very much to the right of the median line, 



(iii) the oviducts instead of originating from the dorsal surface of the ovary and 

 running downwards are found well past the middle of the mantle cavity on the ventral side 

 of the ovary, running first upwards and then downwards. 



The other example, which is very much darker in colour, shewed no such development 

 of the ovary, the gills were more posterior in position and the oviducts pursued a more 

 normal course. The heart, however, is still placed well towards the right-hand side. Com- 

 paring the two examples we may safely conclude that at sexual maturity the extensive 

 development of the ovary tends to displace the organs of the branchial complex in the 

 manner described above. 



In both forms the heart is peculiarly elongate and piriform, the posterior aorta 

 occupying the apex and the two efferent vessels and the anterior aorta the base. 



3. Polyp)US gardineri Hoyle. Fauna and Geography of the Maldive and Laccadive 

 Archipelago (J. S. Gardiner). Cephalopoda. Vol. ii. Supp. i. p. 976. 



One example, <?, from Coetivy, 32 fathoms (1419). 



It was impossible to make any dissection of this example owing to the imperfect state 

 of preservation. Superficially it agrees in all respects with Hoyle's type description, the 

 lateral arms exhibiting enlarged suckers (v. supra, p. 437). 



Hoyle supposed that this form might possibly be the young of P. fontanianus ; but 

 comparison of the radula of these two forms does not support this possibility. 



