CALCARBA. 5 



of the flagellated chambers. The flagellated chambers touch each other only at the 

 corners and have no intercommunication canals. Serial tangential sections show that 

 each flagellated chamber opens independently into the gastral cavity. (See 

 Plate XXXVIII, Fig. 137.) This may also be inferred by comparing the distances 

 between the openings into the gastral cavity, shown in von Lendenf eld's Figs. 56 and 

 58, and the distances between the flagellated chambers shown in Fig. 57 (remembering 

 that the rectangles are alternately flagellated chambers and canals). The cross-sections 

 made by the author correspond exactly with the structure above described. It 

 is, therefore, evident that there is no similarity between Sycon tenellum, as it 

 should now be called, and the new genera with " linked " chamlbers. 



The new genus Streptoconus* in the family Staurorrhaphidse, corresponds with 

 Sycon in the Sycettidse. 



The new genera Achramorpha f and Megapogon % in the family Staurorrhaphidse 

 correspond with Grantia and Leucandra in the Grantiidse. 



Dendy's sub-genus Grantiopsis is transferred from the Grantiidse to the Staurorrha- 

 phidse, because the only species ( Grantiopsis cylindrica) contains chiactines. 



Terminology. — The following terms are used to describe the different pores 

 and passages by which the water passes through the sponge : — 



Ostia. — The pores in the dermal membrane through which the water first enters the sponge. 



Prosopyhs. — The openings in the flagellated Chambers by which the water enters them. 



Apopyles. — The openings in the flagellated chambers by which the water leaves them. 



Ports. — This is a new term used to describe the openings in the gastral membrane by which the 

 water passes from the excnrrent chambers into the gastral cavity. 



Pore is only used in a general sense for any of the above. 



Incurrent chambers. — The large spaces sometimes found under the dermal cortex. The water 

 enters them by the ostia and leaves them by the incurrent canals. 



Ineurrent canals. — The passages by which the water reaches the outside of the flagellated 

 chambers. They communicate with the outside water either through the ostia or directly. 



Excurrent canals. — The passages by which the water, leaving the flagellated chambers through 

 the apopyles, reaches the gastral cavity or oscule. 



Excurrent chambers. — The spaces sometimes found outside the gastral membrane into which 

 several excurrent canals or several apopyles open. The water flows out of them through ports into 

 the gastral cavity. 



Oscule.— The opening by which the water finally leaves the sponge. It may be at the end of one 

 or more excurrent canals, or at the top of the gastral cavity. 



Oscular colla/r.—k thin tubular extension of the body wall, without flagellated chambers, leading 

 to the oscule. 



The most interesting features of the collection are : — 



{a) The large number of species (9) containing chiactine spicules. 

 \h) The five new species with " linked " flagellated chambers. 



(c) A remarkable sponge, Megapogon villosus, with larger spicules than any hitherto recorded for 

 a calcareous sponge. The oxea are upwards of 15 mm. long. 



* o-T/jfTTTos, twisted ; Kavos, a cone. t axpas:, a pear ; fiopf^ii, form. 



% fieyas, great ; nayav, a beard. 



