42 Proceedings of the Koyal Physical Society. 



15. Laganum depressum, Less. 

 A. Ag., Rev. Ech., p. 518. 



Localities. — II., Maiyapa Bay, sand, mud, and coral, 10 fathoms ; III., 

 Mtundo Bay, sand, shell, and coral, 6 fathoms ; VI., Kero-Nyuni 

 Bay, sand, 5 to 10 fathoms. 



Many specimens of various ages. In shape these specimens show 

 many of the variations in outline habitual in this species : the truncated 

 angles give a sub-decagonal or sometimes almost orbicular outline. The 

 greatest transverse diameter is just anterior to the anterior pair of 

 ambulacra in the largest specimen ; in the smaller ones, it tends to run 

 posterior to them or across the apex : this is not in accordance with what 

 A. Agassiz describes (loo. cit.). In the larger specimens, the petals are 

 relatively shorter than in the young, and in the largest specimen of all the 

 margin of the test is distinctly swollen. In this specimen the posterior 

 sides tend to show re-entrant angles, and on one side the test has 

 evidently been damaged and partial regeneration, at least to the extent 

 of the upper and lower surfaces fusing, has taken place. 



The largest specimen has these dimensions : — 



Long, dia., 68 mm. Length, ant. pair ambulacra, 17 mm. 



Trans, dia., 65 mm. Length, odd ambulacrum, 18 mm. 



Distribution. — Zanzibar, Mergui, Australia, the Philippines, and 

 Fiji Islands. 



16. Laganum decagonale, de Blainv. 

 A. Ag., Rev. Ech., p. 520. 

 Locality. — III., Mtundo Bay, sand, shell, and coral, 6 fathoms. 



A single dead specimen rather more oval than decagonal in outline. 

 Distribution. — Western Pacific and Bay of Bengal. 



17. Echinodiscus auritus, Leske. 

 A. Ag., Rev. Ech., p. 531. 



Localities. — Kifuki Island and Foomo Island. 



Only one specimen was collected but it is a very perfect one. The 

 outline, especially posteriorly, is somewhat irregular. The edge on one 

 side anterior to the lunule is very ragged and gives the impression 

 that it has suffered injury and has undergone a certain degree of re- 

 generation. The length of the lunule is 40 mm., the total distance from 

 the edge of the test to the apex is 92 ; this is a longer lunule than generally 

 is found. The anus, however, is as usual in a line with the inner ends of the 

 lunules. 



