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PROCEEDINGS OF THE 



[Dec, 1856. 



trunk or proboscis (ff. 1 and 2, a) showing the radiate arrangement of the 

 large pyramidal cells. 



Fig. 8. — A view of the rim of the bell very much magnified, but in a state of 

 strong contraction, so that nothing appears to be left of the tentacula but 

 their bulbs, two of which are seen bearing at their extremities the ocelli. 

 Immediately above at a, is the junction of the very wide vertical and circu- 

 lar chymiferous tubes, which is seen to be simple. 



Fig. 9. — A view of the bulb of a tentaculum with the lash extended, showing the 

 aggregate character of the pigmentary ocellus. 



Fig. 10. — A transverse section of a tentaculum taken across the bulb, showing the 

 ocellus in profile. 



plate 5. 



Fig. 11. — The terminal enlargement of a tentaculum, showing the lashes of the 

 terminal thread-cells extended. 



plate 4. 



Fig. 12. — Two of the thread-cell bunches on the lips brought close together. Much 

 magnified. 



Figs. 13, 14, 15. — Fig. 13 represents the small epithelial cells of the inner surface 

 of the bell. Fig. 14, the elongate cells of the circular muscular tissue. Fig. 

 15, the cells of the external layer overlying the muscular tissues. A and B 

 represent the appearance of these cells in two different lights, in one ot 

 which, B, they appear nucleated ; a, three of the small, round cells, perhaps 

 thread-cells, which are scattered on the outer surface of the animal. 



PLATE 5. 



Figs. 16, 17, 18. — Ova in different stages of development. The two smaller ova 

 in fig. 16 are the youngest I have seen, simple utricles filled with granular 

 content. In the two larger, f. 17, one contains a nucleated, the other a nu- 

 cleolated germinative vesicle. The dark ova in this and f. 18 represent, a 

 stage when the germinative vesicle has become ill-defined from being sur- 

 rounded by semi-opaque, granular substance. 



plate 6. 



The figures on this and the succeeding plate represent various stages of devel- 

 opment of the larva. 



Fig. 19, a and b. — Two outlines of an un-tentaculated larva, the youngest stage 

 observed. 



Fig. 20. — The next or bi-tentaculate stage; p, is the yet imperforate oral bulb; 

 the dark space within, s, represents the digestive cavity and oesophageal 

 canal. 



Fig. 24. — Represents the stage immediately succeeding this, wherein gemmation 

 has already progressed quite far. In the stock-hydra at the point b, is seen 

 the outline of one of the second pair of tentacula just budding from the 

 surface. 



Fig. 25. — Is a larva which has attained its second pair of the tentacula. The 

 space within distinguished by lighter shading is the digestive cavity and 

 oesophageal canal. 



Fig. 25a. — Is a reverted Turritopsis with three larvae clinging to the contracted 

 proboscis. 



a. the hyaline part of proboscis. 



