466 Prof. J. E, Duerden on the 



relationsliip somewhere between Diosaccus, Boeck, and 

 Amphiascus, G. O. Sars, but it appears to be more nearly- 

 allied to the first; it diffi-rs, however, generically I think 

 from both. The outer ramus of the posterior antennae is 

 two-joiiitt'd. The mandibles have the bititij2;-edge armed with 

 distinct though somewhat irregular teeth. The maxillae 

 differ from the same appendages in Diosaccus in being 

 compact in structure (in this respect they more nearly resemble 

 those of Amphiascus) J and the inner branch of the fourth 

 pair of thoracic legs is composed of only two joints. 

 The species appears to be rare. 



EXPLANATION OF PLATE XL 



V Arcythompsonia fairliensis, T. Scott. 



Fi;/. ]. Female, seen from the side. 



J'V//. 2. Male, seen from the side. 



Fig. 3. Mandible and mandible-palp. 



Fig. 4. Foot of second pair, male. 



Fig. 5. Last abdominal segment and furcal joints, female, dorsal view. 



Fig. 6. Last abdominal segment and furcal joints, male, dorsal view. 



PteropsyJlus consimilis^ T. Scott. 



Fig. 7. Foot of first pair. 



Fig. 8. Foot of fifth pair, female. 



Harrietella simuhtns, T. Scott. 



Fig. 9. Female, dorsal view. 



Fig. 10. Foot of fourth pair, female. 



LXIII. — The Morphology of the Madreporaria. — VII. Intra- 

 pohjpul Tentacles *. By J. E. DuEEDEN, Ph.D., A.R.C.S. 

 (Loud.), Professor of Zoology, Rhodes University College, 

 Grahamstown, Cape Colony. 



Coral polyps present remarkably few structural departures 

 from the ordinary Zoantharian t} pe of polyp. Their few 

 characteristic organs are simple, and scarcely any variations 



* The first two parts of this seiies of papers appeared in the * Johns 

 Hopkins University Circulars,' vol. xxi. nos. loo & 157, and were re- 

 printed in the Ann. & Mag. Nat. Hist. ser. 7, vols. ix. & x., May and August 

 1902 ; the third and fourth parts appeared in the Ann. ^Sc Mag. Nat. Hist, 

 vol. X., November 1902, and vol. xi., February 1903 ; the fifth and sixth 

 parts in the ' Biological Bulletin,' vol. vii., July 1904, and vol. ix., June 

 1905. The work is being carried out with the assistance of an appropria- 

 tion from the Carnegie Institution, Washington. 



