76 



No tube accompanies these examples, but in those brought 

 home by the '' Challenger," the structure was as follows : — The 

 tube was dense, composed of entire small shells, coarse fragments 

 of shells, sand-grains and other structures cemented by the tough 

 secretion which also forms a lining to the interior. This lining is 

 in many parts tinted of a dull purple, yet this does not prevent it 

 from being semi-translucent. As in many other tubes in the 

 collection the colour is pale, from the semi-translucent grains. It 

 is thus in contrast with huge and heavy masses formed by a Saln-l- 

 hiria brought from St. Vincent by Dr. R. M. Gunn, composed of 

 agglutinated tubes of coarse yet smoothly worn minute pebbles. 

 The majority are white, but dotted here and there are many 

 minute black pebbles which seem to be less rounded than the 

 white. Such a mass illustrates well the power of Sahellavia io 

 form structures capable of resisting the heaviest surf-waves. 



As indicated in the "Challenger" volume,* an intricate 

 central muscular region occurs in the anterior division of the 

 body, e.g., behind the mouth, and it is especially regular and 

 beautiful in connection with the two median and two lateral 

 channels in the dorsal region. The nerve-cords are internal 

 and abut on the perivisceral chamber. Behind the foregoing 

 the circular muscular coat is well-developed. The dorsal longi- 

 tudinal muscles are much more massive than the ventral and 

 are continuous over the vascular channel in the median line. 

 The separate nerve-cords lie on each side of the median line. 

 In the posterior region the dorsal and ventral muscles are 

 proportionally small. The neur.il canal lies at the inner and 

 inferior region of the nerve-cord. The great central area of 

 the body is occupied by the distended alimentary canal, with 

 the reproductive organs at the sides. 



The contents of the alimentary canal consisted of sandy 

 mud, numerous sponge-spicules, a few diatoms and organic 

 fragments, besides many Gregarime. 



The same species was found by Marenzeller t in the collec- 

 tion from Angra Pequena on the West Coast. 



Fam. AMPHICTENID^. 



Pectinaria Capensis, Pallas, 1766. 



1766. Nereis cyliiii/riiyid, Pallas, jNIiscell. Zool. p. 117, Tab.. 

 IX, f. 1-2. 



A large species measuring in spirit about 150 mm. in^length, 

 and having a diameter behind the pale?e of fully 12 mm. 



* Op cit., p. 420. j'/a)u\. Jahrb. III., p. 21 (scp. :ibdr.). 



