GIGANTOCYPRIS MVLLERI 193 



the attachment of the foremost limbs at the top of the labrum and the heart, has become 

 spread out, and it is this region which shows the most important structural peculiarity 

 of Gigantocypris . 



In Doloria this space is occupied by a normal-sized nauplius eye, from the middle of 

 which projects a finger-like frontal organ (dotted in Fig. la, and Cannon, 193 1, 

 text-fig. 2). Abutting on either side are the normal-sized paired eyes. These, in side 

 view, appear to occupy a triangle bounded posteriorly by the attachment of body to shell, 

 anteriorly by the shell itself, and ventrally by the antennae. In Gigantocypris this triangle 

 is very large, but instead of the paired eyes enlarging to occupy it these have dwindled 

 to vestigial sacs, while it is the nauplius eye which has enlarged. 



This extraordinary organ was erroneously called the frontal organ by Miiller (1895, 

 p. 159), a mistake that was corrected by Luders (1909, p. 119), who gives a fairly com- 

 plete description of the organ. Neither worker identified the true frontal organ. This 

 I have identified from its nerve supply as a minute tubercle situated on the lower median 

 edge of the nauplius eye, about half-way between the tip and the upper limit of the 

 labrum (Figs. 16, 12, and Plate XLI, figs, i, 3). 



The shape of the nauplius eye has never been accurately figured. Miiller (1895, 

 p. 159) refers to it as " nasenformiger Korper", and it certainly can be compared with 

 the human nose. The median ventral ridge, which bears the minute frontal organ, can 

 be compared with membranous septum or columna nasi. The alae or membranous 

 outer walls of the nostrils are represented by lateral spherical bulges just above the 

 paired eyes which extend forwards to the narrower median ridge of the nose. I have 

 attempted to show this shape in Fig. ya, and it can be seen very faintly in Plate XXXIX, 

 fig. 1. Usually in preserved specimens the extremely thin membrane which covers the 

 eye has collapsed, but in the specimen photographed and in a celloidin series of sections 

 it remained undisturbed. 



SWIMMING AND FEEDING 



From its shape and actual size it may be safely deduced that Gigantocypris is unable 

 to move quickly through the water. It is not accurately spherical as it is slightly 

 " stream-lined ", but even so, its enormous size — the size of a cherry — makes it impossible 

 for it to move under its own power with any speed. Specimens collected on the expedi- 

 tion have frequently arrived living at the surface, and Dr Kemp has had several 

 opportunities of observing them alive. In a letter he states: "...we have had them in 

 bowls of sea-water on various occasions, and I am sure that they are not capable of 

 any rapid movements — as indeed one would guess from their shape. They rock and 



roll a lot, finding it difficult to keep on an even keel, and swim feebly " Despite this 



they feed on most active prey. One specimen contained the remains of two giant 

 Sagitta, while it held a third in its mandibles, and another contained the telson and two 

 somites of a Brachyuran zoaea. Dr Seymour Sewell kindly examined slides of the gut 

 contents of a third specimen and among the Copepods found two ". . .examples of 

 Pleuromamma robusta Dahl, male ; in addition to these two specimens there were the 



