24 Mr. H. J. Carter on the Subspherous Sponges. 



ability, long experience, and the advantages afforded by the 

 British Museum for reference both to specimens and ])ublica- 

 tions, we could not have a better authority in point of classi- 

 fication ; but, of course, this must depend very much upon the 

 assertions of others, which, if incorrect, reflect dishonour upon 

 those with Avhom they originated, and not upon the author of 

 the classification. 



In offering the few remarks above mentioned, I do not pre- 

 tend to comment on the subject generally ; and should it here- 

 after be found that my Tethya arabica and G-eodia arabica are 

 one and the same respectively with the T. cranium and G. 

 zetlandica of our own shores, which, on more careful examina- 

 tion of the latter, I do not think unlikely to be the case, it will 

 be so far fortunate that the species have been thus reduced, 

 and my names obliterated, feeling as I do conscious of the 

 but too melancholy conclusion expressed by Raspail, at the 

 end of the preface to his ' Diet, de Termes des Sciences Natu- 

 relles,' that " La science ne marche que par la nouveaute des 

 faits ; et la nouveaute des mots, ou la rend stationnaire ou bien 

 la fait retrograder." 



EXPLANATION OF PLATES I. & 11. 



N.B. All the figures in these plates are more or less diagrammatic, for 

 convenience of illustration, except the drawings of the four Sponges them- 

 selves, which are delineated after nature. 



The measurements (of course, approximate") are given in units indi- 

 cating so many ISOOths of an inch, or in fractions of these, imless other- 

 wise stated, by which the relative proportions in size of the objects can 

 be seen directly, and the real ones readily ascertained by computation, if 

 desired, 



Plate I. 



Fig. 1. Tethya arabica, n. sp., natural size, showing the hispid state of 

 the surface and three large vents. 



Fi(]. 2. The same, section to show internal structure : «, matted sponge- 

 substance of surface supported on the distal portions of four 

 kinds of spicules terminating respectively in single-pointed, 

 bifid and trifid extended, and trifid recurved extremities ; 

 h, sponge-substance of body supported on bundles of spicules 

 overlapping each other, which radiate from the centre to the 

 circumference, and present between them the truncated canals 

 of the efferent or excretory system; c, nucleus, consisting of 

 densely matted sponge -fibre interwoven with intercrossing 

 spicules. 



Fig. 3. The same, portion of surface magnified, showing reticular arrange- 

 ment of the lines of spicules with pores in the interstices. Seen 

 only in the fresh or undiied state. 



Fig. 4. The same, forms of the distal extremities of the spicules of the 

 surface, respectively, all smooth and straight : rt, stout, fusi- 

 form, pointed at both ends, 250 long by 2^ broad (that is, 



