248 PROCEEDINGS OF THE ACADEMY OF [1887. 



therefore, in this region, as well as in Nova Scotia and New Found- 

 land must be considered as at least occasionally perennial. 



(IV.) Gen. TTJBELLA, Carter. 



Gen. char. Skeleton spiculse as in the foregoing genera, but some- 

 times hemispherically rounded at the extremities. Gemmulse glob- 

 ular or elliptical; apertures lateral or terminal. Granular crust 

 charged with trumpet-shaped ina^quibirotulate spicules, of which the 

 larger rotule rests upon the chitinous coat ; the size of the outer 

 rotule smaller, but bearing a variable relation to that of the foi'mer. 

 The margins of the larger rotules generally entire. 



The genus Tubella was created by H. J. Carter in 1881 with four 

 species, all from the River Amazon, in South America ; one of 

 them was of his own naming; the remaining three having been prev- 

 iously described (as Spongillas), by Dr. Bowerbank. The new 

 genus was needed to separate those sponges having markedly un- 

 equal birotulates, from the typical forms of Meijenia. The discovery 

 in Pennsylvania during the same year, of a fifth species and after- 

 ward of its wide distribution throughout the United States, tends to 

 approve this necessity. Ann. and Mag. 1881, p. 96. (PI. VI, fig. ii.) 



KEY TO THE SPECIES OF THE GENUS TUBELLA. 



1. Insequibirotulate or trumpet-shaped sjiicules of two forms, upon 

 separate gemmules. The shafts of one form stouter and bear- 

 ing a larger distal rotule than that of the other. Flesh spicules 

 wanting. T. paulula. 



2. Shafts of trumpet-shaped spicules long, nearly cylindrical, 

 spiniferous. Flesh spicules entirely spined. T. spinata. 



3. Sponge structure rigid; terminations of skeleton spicules rounded. 

 Gemmules surrounded by a capsule of sjiined spicules, much 

 smaller than those of the skeleton. Shaft of trumpet-shaped 

 spicules short, with a ring-like inflation near the larger rotule. 



T. reticulata. 



4. Birotulates in two zones, i. e. trumpet-shaped next the chitinous 

 coat, surrounded by a zone of short, robust spicules with equal 

 rotules of eight recurved teeth or rays. T. recurvata. 



5. Skeleton spicules spiniferous. No dermal spicules. Rotules of 

 trumpet-shaped spicules flat or twisted ; margins generally en- 

 tire ; shafts smooth. (PI. VI, fig. ii.) T. pemisylvanica. 



(1) Tubella paulula, Carter. Ann. and Mag. 1881, p. 96. 



Spongllla paulula, Bowerbank. Proc. Zool. Soc. etc., 1863, p. 453. 



