152 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



points, which may be sharp and conical or more or less truncated or 

 rounded off. 



Zooids closely resembling those of D. grande. They are small 

 (about 1 mm. long in their contracted state) and have a tapering 

 muscular process extending out into the test from the constricted 

 neck connecting the thorax and abdomen. Branchial siphon rather 

 large, with six short triangular lobes. It is lined with test sub- 

 stance which may contain spicules. 



Tentacles of three sizes. 



Branchial sac with four rows of stigmata, eight on each side in 

 the anterior rows and 7 in the last row. 



Dorsal languets arising from the transverse vessels a little way to 

 the left of the median dorsal vessel. 



No pecularities noted in the digestive organs. 



No reproductive organs found in the zooids examined. 



The above-described specimens are from: 



No. 16. Station D5145 (near Jolo Light, Feb. 15, 190S, 23 fathoms, coral 

 sand and shells). Two colonies (Cat. No. 5880, U.S.N.M.). 



No. 18. Station D5174 (off Jolo Light. Mar. 5. 1908, 20 fathoms, coarse 

 sand). One large colony (Cat. No. 5881, U.S.N.M.). 



Herdman (1886) described the species from Zamboanga, Min- 

 danao, 10 fathoms. Sluiter (1909) records it from one station in the 

 Sulu Archipelago (latitude 6° 7.5' N.; longitude 120° 26' E., 16-23 

 fathoms) and from other localities in the Malay Archipelago. 



DIDEMNUM TERNATANUM (Gottschaldt). 1898. 



Plate 28, fig. 16 ; plate 29, fig. 17 ; plate 30, figs. 24 and 25 ; plate 33, fig. 44. 



1898. Did-eninum ternatanum Gottschaldt, Abh. Senckenburg. Gesell., vol. 



24, p. 648, pi. 35, fig. 1. 

 1909. Didemnum ternatanum Haktmeyeb, Bronn's Tier-reich, vol. 3, suppl., 



p. 1451. 



Though subject to much modification in shape, due to the position 

 in which it grows and the form of the object to which it is attached, 

 this species is generally recognizable by the thick, fleshy, cushionlike, 

 dome-shaped, or obtusely conical colony with a single large common 

 cloacal aperture at the highest point. The zooids of such a colony, 

 even when it is large, therefore form a single very complex system. 

 This makes necessary large branching cloacal canals in the super- 

 ficial parts of the colony, and these, together with the rather soft, 

 weak character of the test substance, render the colonies more fragile 

 and more easily torn (especially in the superficial parts) than those 

 of related species described in this paper. When a colony has a base 

 of irregular or elongated form there may be two or three common 

 cloacal apertures, and these are then commonly on distinct elevations 

 or prominences. In some colonies, the courses of the common cloacal 



