Species of Donatia (Tethya). 15 



no hesitation in recognizing these Bermuda varieties as 

 specifically distinct from the Bermuda Donatio, seychellensis, 

 though they possess practically the same spiculation. 



Variety A. — In the same habitat as has been described for 

 D. seychellensis there was found, a little later in the season, 

 an abundance of bright green spherical sponges slightly 

 larger than D. seychellensis. On the 1st of September, when 

 D. seychellensis was fairly numerous and even beginning to 

 bud, only occasional specimens of the green form were 

 obtained, and it was not until Sept. 18 that the first bud was 

 seen. The surface of these sponges is raised into rounded 

 hillocks, which are themselves composed of smaller rounded 

 elevations. The cortex is much more fleshy and dense than 

 that of D. seychellensis, and is solid, instead of showing a 

 network of strands between the conules. The colour is 

 uniform over the entire surface, with a slight variation 

 among different individuals from dark bright green to a more 

 nearly olive tint; in alcohol it is pink to light orange. 

 There is a range of diameter from 11 to 32 mm., though 

 specimens larger than 25 mm. are exceptional. The buds 

 are clear bright green, and their form and arrangement are 

 as in D. seychellensis. There are usually either one or two 

 oscula, occasionally three or more, and in case of two or three 

 they have a typical arrangement side by side 1 to 2 cm. 

 apart. They are exceedingly conspicuous structures by 

 reason of the modification ot the conules about the oscula 

 into long plates, which stand up around the opening and may 

 project as much as 1 cm. beyond the general surface of the 

 animal. A cross-section of this sponge shows the cortex to 

 have twice the thickness of that of D. seychellensis ; it consists 

 of a thin, white, fibrous inner layer and a very thick, fleshy, 

 green layer. The choanosome is dark yellow, and has at its 

 centre a ■white fibrous core about 2*5 mm. in diameter, from 

 which the radiating bundles proceed and spread out beneath 

 the conules. 



The spicules are in form and size similar to those of 

 D. seychellensis, but differ somewhat from the latter in 

 distribution and especially in the degree of branching of the 

 oxyasters. (1) The megascleres are strongyloxeas, with the 

 ecactine very frequently rounded, and range from - 35 to 

 1*6 mm. in length and from 6'6 to 23 fx, in diameter. 

 (2) Spherasters similar to those of D. seychellensis are fairly 

 frequent in all regions of the sponge and are exceedingly 

 numerous in the cortex. (3) Chiasters are numerous 

 throughout, and especially abundant in the cortex, at the 



