H0L0THUR10Il)EA. 1)3 



Tlie calcareous ring is small, being only 4 millinis. long. It is composed of ten 

 separate pieces. The radials are notched anteriorly and bifurcated posteriorly. Each 

 posterior prolongation is composed of about four small pieces. The inter-radials are 

 simple (tig. 11). 



There is one stone canal and one Polian vesicle. There are no gonads present in 

 this specimen and the alimentary canal is eviscerated. Both the right and the left 

 branches of the respiratory tree are well developed. There are no anal teeth. 



Deposits : These are very scarce, and imperfectly formed. This leads me to 

 believe that the animal may have been preserved originally in formol, but I have no 

 record of this. The deposits are small plates having many holes, and probably 

 slightly hollow (tigs. 12 and 13). These are very rare. The pedicels have well- 

 developed terminal plates. 



Owing to the tentacles being absent, I am unable to assign the specimen to its 

 genus with certainty, although it is, in all probability, a T/iyone. 



Thyone (?) hornelli, n. sp. Plate I, tigs. 14-10. 



One specimen from the lagoon inside the Reef, Galle. 



Length, 50 millims. ; breadth, 20 millims. 



It is broader at the anterior end, and is slightly narrower at the posterior end. 



The colour of the formol specimen is light brown, spotted irregularly with small 

 black marks. The sucking discs of the pedicels in some parts of the body are of a 

 rusty-red colour, and in other parts they are the same colour as the general 

 integument. Beneath the brown epidermis the skin is of a very light violet hue. 



The pedicels, which are large, numerous and well formed, are irregularly distributed 

 over the body, showing no arrangement into rows. There are no papillae. 



The tentacles are absent, and there are no anal teeth. 



The calcareous ring is composed of five radial pieces and five inter-radials, which 

 are, however, not clearly separated from one another. The radials are notched 

 anteriorly and are bifurcated posteriorly, the posterior prolongations being composed 

 of several smaller pieces. The calcareous ring is fairly massive, being 15 millims. 

 long (fig. 14). There is one Polian vesicle and one stone canal. 



The gonads are attached to the dorsal mesentery in one bunch. 



The right and left branches of the respiratory tree are large, and both extend to 

 the anterior end of the body. 



The internal organs and mesenteries are coloured a light violet, like the skin. 



The longitudinal muscle bands are very well developed. 



Deposits : The spicules are very thinly scattered, and consist of small perforated 

 plates having a spiny surface (figs. 15 and 16). Since the animal has been preserved 

 in formol, it is doubtful whether this was originally the exact shape of the deposits. 



T cannot be quite certain as to the genus of this form since the tentacles are not 

 present, but it is probably a Thyone. 



2 C 



