20 DR. J. S, BOWERBANK ON HYALONEMA MIRABILE. [Jail. 10, 



longitudinally, and at equal intervals on the internal sides of the 

 cavities. 



Thus under the last two heads we have a description of forms of 

 siliceous spicula and modes of their disposition in perfect accordance 

 with well-known spongeous organization ; and in truth the whole of 

 the aiithor's descriptions of the Portuguese specimens are stronglv 

 in favour of their spongeous nature, both as regards the material of 

 which the spicula are composed, as well as in their mode of dispo- 

 sition on the outer surface of the corium or bark, which is in perfect 

 accordance witli the external defensive systems so frequently ob- 

 served among sponges. 



No specific characters of Tlyaloiiema lusilanicum are given to 

 distinguish it from //. mirahile ; and it would not at all surprise 

 ine if, upon a further knowledge of the characters of the former, it 

 were to prove to he the same species as the latter ; no forms of spi- 

 cula are given to enable us in the slightest degree to se})arate tlie one 

 from the other. 



Oth.er naturalists have published works on Ilyalonenia — Prof. 

 John Frederick Brandt of St. Petersburg in 1859, Prof. Max 

 Schultze in 18G0, and Dr. Leidy of the United States; but as I have 

 not seen the specimens described by these authors 1 shall confine 

 my observations to the type ones of the genus in Ihe British Museum 

 and others which I have had the opportunity of closely examining. 

 The opinions of the authors who have written on these subjects vary 

 considerably from each other ; but none of them, I believe, enter- 

 tained the idea that Hyalonema was neither more or less than a 

 sponge in all its parts. 



In 1860, while searching for new forms of spicula and other struc- 

 tural peculiarities of the sponges to assist rue in the construction of 

 a systematic nomenclature by which the si)ecies might be described, 

 as plants are in botanical science, I became acquainted with the spe- 

 cimens of Ilyaloncma in the British Museum ; and in the course of 

 a minute examination of the one with the basal mass of sponge I 

 found numerous forms of siliceous spicula which I had not hefore 

 seen, and which I afterwards figured and described in the * Philoso- 

 phical Transactions of the Royal Society of Londou' for 1862. 

 Figures 3, 4, .5, and 6 in plate 31, and figures 12, 20, 30, 34, 35, 36, 

 37, and 38 in plate 36, are all from the specimen in the British 

 Museum ; and the result of this examination of the specimen was a 

 stron^ conviction that the whole of the parts formed but one animal, 

 and that it was truly a sponge. This conviction I published in the 

 third part of my paper " On the Anatomy and Physiology of the 

 Spongiad(p" in the ' Philosophical Transactions of the Royal Society' 

 for 1862, p. 1 113 ; and as the description of the genus given liy Dr. 

 Gray applied only to a part of the animal instead of to the whole of 

 it, I deemed it necessary to enlarge the generic characters so as to 

 embrace the whole of the most important parts of its structure, in 

 the following manner : — 



" Skeleton an indefinite network of siliceous spicula, composed of 



