204 Mr. H. J. Carter on the Polytremata. 



to have incorporated so many spicules, both entire and frag- 

 mentary, as to lead to the idea that the latter had been turned 

 to account for strengthening the structure of the test generally. 



Propagation. The circumferential cavities near the base in 

 two of my specimens having been broken open, presented in 

 one instance a great number of free, white, crystalline rough 

 globules of different sizes below the 1000th of an inch in dia- 

 meter, which, under the magnifying-power just mentioned, 

 showed a radiated structure like those in some of the Compound 

 Tunicata, to which they no doubt belong ; while the radii in 

 the fully developed ones being ovoid acuminated, with the 

 sharp end towards the centre, gives a form which cannot be 

 identified with any figured by Prof. Giard [loc. cit. pi. xxii.), 

 nor with any that I have found on the south coast of Devon. 

 How these have come where they now are (that is, whether 

 they have been developed there by an embryo of one of the 

 Compound Tunicata, or drawn in by the pseudopodia of the 

 Polytrema), I have not means of determining. But at first 

 they looked so much like the oviform bodies common to the 

 chambers of the Foraminifera, while they are so far removed 

 from the large cavities containing the spicules, that, had I not 

 known the ova of Foraminifera to be soft, nucleated, and of a 

 yellowish colour, the white frosted appearance of these globules 

 might not have led to that examination which proved them to 

 belong to one of the Compound Tunicata. 



In the other instance the cavities broken open contained 

 several fixed^ circular, obtusely conical bodies of a yellowish 

 colour, scattered over their surfaces (PL XIII. fig. 9, a i), 

 and varying in size below the 332nd ]3art of an inch in dia- • 

 meter both in breadth and height, the largest of which in 

 situ (when viewed by reflected light) presents a lobed form 

 with a dark point in the summit, something like a hole 

 (fig. 9, a). The smaller ones (fig. d,hbb) are not lobed, but, 

 when mounted in situ (that is, on a fragment of the test, 

 fig. 9), and viewed witli a high power by transmitted light, 

 present a minutely corrugated transparent envelope more or 

 less filled with minute, granular, opaque material, also fur- 

 nished with a dark point like an aperture at the summit. 

 Whether the "lobed" larger ones are or are not a more 

 developed state of the unlobed smaller ones, or whether or 

 not they are all the same, and all embryos of PoJytrema 

 halaniforme^ there is nothing to determine beyond what has 

 been mentioned, and that for the most part they are based 

 on one or two spicules adherent to the surface of the cavity 

 of the test in which they are situated. 



Lastly, a single embryo (fig. 8) was found outride the test 



