AND PHYSIOLOGY OF THE SPONOIAD^. 
831 
shaft acting as a skeleton-spiculum, while the ternate apex serves as a defensive spi- 
culum. 
Gexiculated expando-teenate (Plate XXXVI. fig. 10). — From Tetliea CollingsU, 
Boweebane, ms. Sark. The shaft acts as a subsidiary skeleton-spiculum, and the 
ternate apex as a defensive one. 
Abbeeviato-patexto-teexate (Plate XXXVI. fig. II). — From a sponge allied to 
Pachymatisma, in the Museum of the Poyal College of Surgeons, London. External 
defensive. The example figured is a fully-developed spiculum. 
IXFLATO-FUSIFOEMI-ACEEATE, ASCEXDIXGLY HEMI-SPIXOUS (Plate XXXVI. fig. 12). 
From Hyalonema mirabilis, Geay. British Museum. These spicula are projected in 
great numbers from the dermal surface of the body of the sponge, the smooth basal 
half being immersed in the tissues beneath the dermal membrane, and the spinous 
distal portion projected beyond it. The form and mode of disposition of the spines 
indicate its purely defensive character. 
Veeticillately spixed cylixdeical (Plate XXXVI. fig. 13). — This spiculum is very 
abundant on the dermal and interstitial membranes of an undescribed sponge from 
Freeman tie. Western Australia. It is both externally and internally defensive. 
SuB-ATTEXUATO, EXTiEELY SPIXED CYLIXDEICAL (Plate XXXVI. fig. 14). — From Ily- 
mmiacidon CliftonU Boweebaxk, MS. Freemantle, Western Australia. Internal 
defensive. 
SpICULATED IXEQUI-AXGULATED TEIEADIATE, with cylixdeical EXTIEELY SPIXED EADII 
(Plate XXXVI. fig. 15). — From a fragment of a sponge presented to me by Mr. 
ViCKEES of Dublin, who thinks it probably came from the West Indies. This spiculum 
is an external defensive one. The triradiate rays are imbedded immediately beneath 
the dermal membrane, and the spicular ray is projected through it at right angles to its 
plane ; they are very numerous. 
SpICULATED ATTEXUATO-EQUIAXGULAE TEIEADIATE, VEETICILLATELY SPIXED (Plate XXXVI. 
fig. 16). — From an undescribed sponge. Freemantle, Western Australia. I have not 
seen the sponge whence this spiculum is derived, but, reasoning from our knowledge of 
the form and situation of the spiculum represented by fig. 15, there can be little doubt 
of its being an external defensive one. 
SpICULATED CYLIXDEO-EQUIAXGULAE TEIEADIATE, VEETICILLATELY SPIXED (Plate XXXVI. 
fig. 17). — From a fragment of sponge from Freemantle, Australia. This spiculum 
occurs in the same slide of sponge-spicula as the form represented by fig. 16. It was 
sent to me by my friend Mr. Geoege Cliftox, of Freemantle. There can be little 
doubt of its being an external defensive organ. 
Ixequi-fuecato-teieadiate (Plate XXXVI. figs. 18 & 19). — These forms of spicula 
are from a new species of calcareous sponge, probably a Grantia. They were sent to 
me, mounted in Canada balsam, by my friend Mr. Geoege Cliftox, of Freemantle, 
Australia. They occur loosely fasciculated, and their mode of disposition is very similar 
to those represented by figs. 4 & 5, Plate XXXVI. They differ considerably from each 
