384 



DISCOVERY REPORTS 



parent, tough, and traversed by a network of thick fibres. The body is elongate-ovoid, 

 the head very narrow and the eyes, as usual, closely set on the dorsal surface, and 



very prominent. The arms were probably subequal; 

 but they are badly damaged. They attain a maximum 

 of 67 per cent of the total length. The suckers 

 are uniserial and widely spaced (about 14 mm. apart 

 at the widest). The ends of the arms are damaged, 

 but the suckers seem to have been alternating towards 

 the tips. At about the thirteenth they become much 

 larger. They are of a very simple structure and very 

 thin walled. Except in Melanoteiithis I have never 

 seen such an undifferentiated type. There must 



Fig. 1 1 . Amphitretus thielei. Inferior 



mandible. (The pigmented streaks on , , \ ^ c . /•^\ 1 



. , , , . , , have been about rorty (.'') on each arm. 



one side have been omitted.) J \ J 



The web is about half as deep as the arms and 

 may have been subequal. The funnel is, as usual, adherent to the cephalic tissues, 

 and extends well beyond the eyes. Its organ is large and broadly W-shaped. There 

 is no trace of a valve. 



The gills have seven to eight filaments in each demibranch. They are long and narrow 

 and the inner demibranch is very much reduced, being but half as deep as the other. 

 The mandibles are very weak and imperfectly chitinised. They are not so much splayed 



Fig. 12. Amphitretus thielei. (a) Radula, (b) Mandibles. 



out as in Thiele's figure of A. pelagiais, and differ in many details, especially in the 

 arrangement of the thickenings on the edge of the lower jaw (cf. Fig. 11 and Thiele, loc. 

 cit., fig. 65). The radula differs in many respects from that figured by Thiele, especially 

 in the second and third laterals. The vaginae are remarkably thick and large. They are 

 clearly demarcated from the small spermathecae. 



Remarks. The position of this form is very perplexing. So far a single species of this 

 genus [A. pelagicus) has been observed. It was first described by Hoyle (1885, p. 235, 



