REPORT ON THE OPHIUROIDEA. 41 



none, can be seen from the upjDer surface. Three small, nearly equal, peg-like arm spines, 

 less than half the length of a side arm plate. Five small, close-set tentacle scales to 

 pores of mouth tentacles, three on one side and two on the other ; the pores beyond have 

 but one small rounded scale. Colour in alcohol, straw. 



Station 317.— February 8, 1876; lat. 48° 37' S., long. 55° 17' W. ; young; 1035 

 fathoms'; hard ground. Station 320.— February 14, 1876 ; lat. 37° 17' S., long. 53° 52' 

 W. ; 600 fathoms ; hard ground. 



The specimen described, though well characterised, was perhaps not fully grown. It 

 is the southern cousin of Ophioghjpha robusta, from which it differs in shorter arm 

 spines, more swollen disk scales, smaller mouth papillae, and fewer tentacle scales. 



Ophioghjpha multispina, Ljn., Oph. Viv. Of. Kong. Akad., p. 307, 1866 ; Lym., 

 Bull. Mus. Comp. Zool., vol. v., part 7, p. 99. 

 Port Jackson, Australia; 2 to 10 fathoms. 



Ophioghjpha hexactis, E. A. Smith (PI. XLV. i5g. 1 ; PI. XLVII. fig. 2). 



OpMoglyplia hexactk, E. A. Smith, Ann. Mag. Nat. Hist., vol. xvii. p. 3, Feb. 1876; Lym., 

 Bull. Mus. Comp. Zool., vol. v., part 7, p. 99. 



In the whole genus this is the only species that has more than five arms. It is 

 also viviparous. A curious parallel is the many-armed Ophiacantha vivipara, from the 

 same region, which is viviparous likewise. But whereas the bursse of the latter are 

 limited to the neighbourhood of the arms, those of the species under consideration are 

 thrust between the disk roof and the digestive cavity, until in some cases they occupy 

 almost the whole body cavity proper, a state of things shown in fig. 1, Plate XLV., 

 which presents a vertical cross-cut of a gravid female, passing through one arm and the 

 opposite interbrachial sj^ace. Just above the mouth angles is the long fold of the mouth 

 sphincter (du), continued on either side by a wide flattened somewhat pleated digestive 

 cavity, whose walls are thin and membranous in some places, where their soft layer has 

 been scraped off. Above this is a space like the low between-decks of a ship, wherein 

 are stored the large young, two of which (Y,Y') are seen cut in two, together with parts 

 of their arms. One (Y) is in a natural position, while the other (Y') lies on its back. 

 Both show the mouth angles beginning to take form, and the large mouth tentacles. 

 Their digestive cavities, simple in the adult, are folded in a way that calls to mind 

 Gorgonocephahis. At first sight these young seem lying free in the body cavity. Each, 

 however, is enclosed in a thin bag, an expansion of the bursa (a fold of it is seen at 8'), 

 which has thrust itself between the disk roof and the upper wall of the digestive cavity. 

 These two surfaces are closely connected normally by threads {sm), which in the present 

 case arc not broken, but simply stretched, sometimes to an immense extent. The rela- 

 tion of the parts may be made clearer by removing the roof of the disk and showing 



(zool. CHALL. EXP. — PAET XIV. — 1882. 6 



