and Acapidco Sponges. 361 



tions, publislied two memoirs entering far more satisfactoril/ 

 than any one who had preceded him into the general descrip- 

 tion of the microscopic characters and reproduction of Tethya 

 {Donatio) lyncurium (Archiv f. mikroskop. Anatomic, Bd. 

 xvi. S. 626, Taf. xxx.-xxxiii., and Bd. xvii. S. 151, Taf. xii.). 

 But in no instance has that spiniferous character of the 

 ray been particuhirly noticed which is represented in my 

 figure from a specimen of the British species found at this 

 place ('Annals,' 1869, I.e. p. 27, pi. ii. Hg. Q,h), to which I 

 would now call attention, because its pointed and spinous form 

 if enlarged would be analogous to that of no. 3 in Donatia 

 multifida (fig. 22, f/), and to that which we shall see hereafter 

 becomes a character in the Cape species or variety. Sometimes 

 the spines in the British species cover the end of the ray in 

 the small staple stellate to such an extent as to simulate the 

 presence of a globular inflation, which is actually the case in 

 the Adriatic form (Bela Dezso, op. cit. Bd. xvi. fig. 4), also 

 in the Australian ones, as I learn from Dr. Bowerbank's 

 figures [loc. cit.) as well as ray own slides, and, indeed, in 

 Donatia multifida (PL XII. fig. 22, e). Bat it is in the Cape 

 species, which is more robust than any of the rest in its adult 

 state as well as in its spiculation, that the three forms of 

 flesh-spicules mentioned in Dotiatia multifida become most 

 distinct, where " no. 2 " (referring to the numbers in the 

 description oi D. multifida)^ the largest, viz. the globostellate, 

 measures 30-6000ths, '^ no. 3," the stclliform, with spinife- 

 rous rays, 12-6000ths (PL XII. fig. 23), and " no. 4," the 

 minute sexradiate, 3-6000ths of an inch in diameter respec- 

 tively. In the specimen from Mauritius " no. 3 " is only 

 O-6000ths incli in diameter ; so that after all the differences 

 are only in degree, and those only sufficient to form a variety. 

 Still, hitherto it does not appear to me that this third form of 

 flesh-spicule, viz. no. 3, so characteristically developed in the 

 Cape species (fig. 23), has been publicly noticed. 



Respecting varieties in spiculation, however, it should 

 always be remembered that our observations are necessarily 

 very limited, on account of their having to be made on perhaps 

 only one or two fragments of the entire specimen, and that 

 specimen perhaps the only one that can be obtained from 

 tlie locality ; whereas, if our observations had been extended 

 further, our statements might have had to be modified, 

 and therefore should always so far be considered provisional. 

 Perhaps, too, for the same reason, the fragments examined by 

 two individuals respectively raigiit not contain exactly the 

 same form of spicules. 



Here I would also notice that the ''globo.itellate" ("Notes," 



