THE ALCYONARIA OF THE CAPE OF GOOD HOPE AND NATAL. 583 



Malacacanthus rufus, nov. gen. et spec. 

 Plate I. fig. 6. 



This form appears to possess features sufficiently distinctive for the founding of a 

 new genus. Its most remarkable character is the apparent absence of spicules. In 

 many other features it approaches the genus Anthomastus ; the latter, however, is 

 regarded as a deep-water form. 



Diagnosis. — Colony agariciform, consisting of a sterile trunk with a somewhat 

 fibrous rind, and a sharply defined, hemispherical, polyp-bearing part. Zooids with 

 distinct dimorphism. Autozooids numerous, much larger than the siphonozooids, and 

 not more abundant at the margin than at the centre of the " pileus." Autozooids 

 retractile within the calyx, which merges imperceptibly into the coenenchyma. Spicules 

 apparently absent. 



This description is based on two specimens, a large and a small one. The general 

 shape of the colony is agariciform, consisting of a stout trunk (stipe) with a strong, 

 fibrous, outer rind ; and a head (pileus) bearing numerous autozooids and siphonozooids. 

 The specimens showed autozooids in all degrees of expansion and contraction. The 

 autozooids are not more numerous at the margin of the " pileus," or the reverse, 

 but those nearer the centre are slightly larger and better expanded. The larger 

 specimen arises from a coralline ground-mass which has a varied collection of animals 

 grouped around it, such as Porifera, Actinozoa, Bryozoa, Sedentaria, Balanidse, 

 Lamellibranch valves and compound Ascidians ; these are reserved for further 

 investigation. 



The general colour of the colony is red, but this varies in tint at different parts ; 

 thus the trunk is of a deeper red than the " pileus," which latter may, as in the 

 younger specimen, be yellowish red. The colony as a whole has a very soft texture, 

 the only portion which has to any extent a firm character being the outer rind of the 

 trunk. The surface of the trunk is very irregular, being marked by depressions, varied 

 longitudinal and transverse lines and wrinkles. The base of the larger specimen 

 expands horizontally into a membrane, which creeps over the ground-surface on which 

 the colony rests. Sections through the trunk show numerous canals connected by 

 smaller ones. No spicules were observed in either of the specimens. As the specimens 

 were preserved in formalin, I thought it possible that the spicules had been dissolved 

 by acid, and I therefore made a number of thin sections from different parts of the 

 colony in order to observe whether spaces occurred in which spicules might have been 

 lodged previous to the preservation in formalin. As a result of this examination, 

 however, I was unable to find any spaces similar to those seen in other Alcyonarians 

 after the dissolution of spicules by maceration. The specimens showed no trace of 

 bad preservation. 



