180 
ON THE SKELETONS OF ZOOPHYTES. 
when obtained quite active from a net, into a vessel of sea-water, where she had 
an opportunity of watching for some time its movements. It glided through the 
water by the alternate elevation and depression of its celluliferous arms, and the 
slight inflections of its stem. The skeleton consists of a straight diconical style, 
situated in the centre of the irritable fleshy body. It is soft and flexible at both 
extremities, to admit of the extensions and contractions which the body performs 
in the longitudinal direction. In the Sea-rush ( Virgularia mirabilis ), the organ 
of support consists of a straight white Calcareous cylindrical boiie, which when 
fractured appears to he composed of Calcareous crystals that radiate from the 
centre like the horny laminae seen on the broken surface of a Belemnite. This 
solid support occupies the centre of the longitudinal axis of the fleshy body, and 
projects for some distance beyond its extremity in Veretillum. The organ of 
support is small, ligamentous, and almost rudimentary. 
The Tubiporidce constitute an interesting group of vaginated Polyps, with a 
Calcareous tubular skeleton. They are in the true sense of the term social zoophytes, 
conjointly forming those beautiful masses of blood-red Coral that decorate with 
their gorgeous hues the bed of the Indian seas. From the observations of 
Lamoukoux* on the Organ Coral ( Tubipora musicd) the type of this family, it 
appears they are destitute of that organic union which exists among the compound 
Polypifera. The skeleton of this beautiful genus consists of a series of bright-red 
alcareous tubes, hound together by transverse septa, so that a colony of these 
little animals presents the appearance of several stages of crimson-coloured pipes 
built upon each other, disposed in parallel rows, and radiating from their common 
attachment, the root. The tubes are placed at considerable distances apart, and 
retained in situ by horizontal laminse of the same Calcareous material as the 
tubular portion of their Polypary. Each tube is a distinct skeleton, and is the 
habitation of a bright green-coloured Polyp, provided with eight foliaceous tenta- 
culse, disposed in a circle round the mouth. The margins of each of these are 
furnished with two or three rows of minute fleshy processes, endowed with great 
sensibility. The animal is attached to its shell by a delicate membrane surround¬ 
ing the base of the tentacules like a collar, from whence it is reflected outwards 
to line the inner surface of that portion of the ttibe inhabited by the Polyp, and 
to become continuous with its free extremity. 
The membrane just described is, therefore, the tube-forming organ, the develop¬ 
ment of the cylinders being due to the gradual Calcification of that portion of the 
gelatinous membrane which joins the extremity of the Calcareous tube. 
The constant deposition of Calcareous matter at the distal extremity of the 
tubes causes their gradual elongation upwards, and necessitates a mechanical 
* Anatomie de Tubipore musical, in C£uoy and Gaimard’s Voyage de VUraine. 
