364 Mr. H. J. Carter's Contributions to our 



p. 83, pi. i. tigs. 1-8), and thus so generally accepted, as before 

 stated, one cannot help considering it, to say the least, un- 

 necessary; hence I shall continue to use Lamarck's appella- 

 tion, viz. Tethya cranium, for the typical illustration of my 



Tethyina. 



The skeletal spiculation of this group, the characters of which 

 are detailed at length in my classification {op. et he. cit. p. 184), 

 only differs from that of the foregoing in the absence of the 

 body-spieule, which, however, appears in a rudimentary state 

 in a species that will be described hereafter under the name of 

 Tethya merguiensis. I have already, however, alluded to the 

 presence of this spicule in Tethyina (/. c), but have never 

 until now had an opportunity of examining and describing an 

 entire specimen in which it is a general character. My first 

 observation of it was in Tethya arabica, where it was partial ; 

 and is thus recorded in the description of that sponge : 

 u In one small portion of the surface which I examined there 

 happened to be several stoutish triradiate spicules with their 

 rays expanded in the circular part, like those of Geodia, show- 

 ing by this occasional occurrence how such characters may be 

 present in species otherwise distinctly different " ( c Annals/ 

 1869, vol. iv. p. 4). I have always regretted that I did not, 

 for preservation and future reference, mount this sponge in 

 Canada balsam ; and therefore, on the next occasion that I 

 met with it, which was in a little mutilated specimen about 

 7-12ths inch in diameter, fixed to a little piece of cardboard 



in the British Museum (no. 452, reg. no. 40. 10. 23. 8), I did 



mount a microscopic fragment that is now before me, in which, 

 however, the form of the zone-spicule and the length of its 

 shaft (PI. XV. fig. 9) shows that it was a different species 

 from Tethya merguiensis (fig. 7 7 bb) 7 although the presence 

 of Carpenteria utricular is and Polytrema with it also pointed 

 to a tropical origin. 



"With reference to the flesh-spicule, it has been stated above 

 that ■ " • - • * •-• -« • 



, in all instances yet known with the exception of one 

 species, viz. Tethya antarctica, Crtr. ('Annals/ 1872, vol. ix. 

 p. 414), this is a minute bihamate ; yet in some cases the 

 form of this bihamate is so different that the differences alone 

 here are sufficient to constitute a specific distinction, ex. gr. 

 Tethya atropuipurea, wherein it is not only unusually large, 

 but furnished scantily with large spines, especially at the ends 

 f Annals,' 1870, vol. vi. p. 176, pi. xiii. fig. 10). The 

 simple bihamate, too, is very frequently microspined all over, 

 although this is not always so evident as in Tethya cranium, 

 var. abyssorum ('Annals,' 1876, vol. xviii. p. 405, pi. xvi. 

 fig. 49) ; while in Craniella tethyotdes, Sdt. (does not the ana- 



