524 EDITH M. PRATT. 



The species approaches Sc. capitate and Sc. densum in that the siphonozooids are less 

 degenerate than in the other species of the genus which I have examined. They are smaller 

 than those of Sc. capitate, but agree with that species in having indications of a double 

 row of pinnules on the tentacles and in that the mesenteries and mesenterial filaments are 

 fairly well-marked, and are longer and broader than those of Sc. densum. 



11. Scterophytum potydactytum (= Atcyonimn potydactyluin Dana, = Lobutaria potydacty- 

 tum Ehrenberg). 



A single complete and excellently preserved specimen, attached basally to a piece of 

 hard coral, was taken at 25 fathoms, Miladuraadulu Atoll. The colony has a marked lateral 

 compression and is 48 mm. high. The capitulum is 80 x 34 mm. broad. The base of the 

 stalk is irregular in outline, the greatest height of the stalk is 26 mm., its breadth is 

 58 X 31 mm. The specimen is of a tough fleshy consistency yielding slightly to pressure. 

 The lobes are long and slender compared with other species, and are slightly flexible. The 

 colour in spirit is a pale brownish-grey. 



The appearance of the colony is very similar to the specimen figured by Klunzinger, 

 1879 (p. 26, Taf. 1, fig. 6) with which it also agrees in the form and character of the 

 spicules. For many years the species has been included in the genus Alcyonium. A study 

 of its anatomy however reveals its generic identity with the newly established genus 

 Scterophytum. 



The spicules are described and figured by Klunzinger, many of them are of the tuber- 

 culated warted type. The spindles average 2 mm. in length and '45 mm. in breadth. Crosses, 

 K and Y-shaped spicules, and a few spiny spindles occur. Clubs are closely packed near 

 the .surface as in other species. 



There are no true siphonozooids in the species. 



The autozooids are very numerous and are regularly arranged on the many lobes. In 

 the furrows between the lobes they are less numerous. The autozooids are very small, their 

 cavities averaging '5 mm. in diameter near the surface. When partially retracted, they are 

 conical in surface view, the tentacles bending over towards the middle. Regularly arranged 

 minute spicules in the form of slender spindles are imbedded in their outer walls, forming 

 conical shields which effectively protect the soft delicate tissues within. Young autozooids 

 arising from endodermal canals are numerous on the tips of the lobes. The tentacles are 

 pinnate but they are all more or less retracted so that it is impossible to count the rows 

 of pinnules. 



The stomodaeum and sipiJionoglyph are similar to those of other species. The mesenteries 

 are all long and slender, but the dorsal ones are the most prominent. The ventral and 

 lateral mesenteries have short, feebly-marked mesenterial filaments, but the dorsal mesenterial 

 filaments are broad, grooved, and of considerable length. I have been unable to find male 

 or female cells in the specimen. 



Canal Systems. The transverse superficial canal system is extremely well-marked. 

 Short, broad, vertical caeca are given off from the large vessels of this system towards the 

 surface, but do not communicate directly with the exterior. There can be no doubt that 

 these caeca are identical in origin and to a certain extent in structure with the degenerate 

 siphonozooids of Sc. capitate, densum, hirtum, and palmatum, but in this species degeneration 

 has proceeded so far that the siphonozooids have no stomodaeal apertures. Traces of stomodaea 



