140 Mr. A. Alcock on 



connexion, by way of the Mediterranean Sea, between the 

 Tropical Atlantic and the Indo-Pacific is to be derived ; 

 corroborative evidence appears to be fnrnished by every 

 group among the ' Investigator ' collections that has been 

 examined. 



(a) Among the Hexactinellid Sponges, which have been 

 determined for us by Professor F. E. Schulze, we find : — 

 (1) AphrocalUstes Bocagei, P. Wright, which is known from 

 the West Indies, from Spain, Portugal, and the Cape Verd 

 Islands, from the North-eastern Atlantic, and from Japan, 

 and has been dredged by the ' Investigator ' in 130-265 fath. ; 

 and (2) Farrea occa^ Carter, which occurs in the West Indies, 

 in Japan and the Philippines, and also off the Andaraans at 

 220-240 fath. 



[h) Among the Madreporarian Corals are Caryophi/llia 

 communis, Seg. Mos., and Flahellum laciniatum, Phil. These 

 two Atlantic species are frequently found in Indian Seas at 

 depths between 200 and 700 fath. As they occur fossil in 

 the Tertiary deposits of Sicily and Southern Italy, they have 

 here a special interest. We also find in the Andaman Sea 

 a Deltocyathus that seems to be nothing more than a variety 

 of the DeUocyatlnis italicas (Mich.), E. & 11., of the North 

 Atlantic and of the Miocene of Nortiiern Italy. 



(c) Among the Ecliinoderms, which liave been named by 

 Dr. J. H. T. Walsh (Holothurians), Prof. R. Koehler (Ophi- 

 uroids), and myself (Starfishes), the following are common to 

 the Atlantic and the seas of India; — Porcellanaster cceruhus, 

 Wy. Thorns., Nymphaster basil icus^ Sladen, Nymphaster pro- 

 tentus, Sladen, (Jphiomusium validam, Ljungniann, Ophiernus 

 adspersus, Lyman, Ophiocamax fasciculata, Lyman, Astronyx 

 Loveni, M. & T. (also occurs in Japan), Eupyvgus scaber, 

 Liitk. (also occurs in Arctic Seas). None of these are true 

 abyssal forms. 



[d) Among the Crustacea the following, four of which 

 were determined by the late Prof. J. Wood- Mason, are 

 common to the seas of the East and West Indies and neigh- 

 bourhood : — Bathynomus giganteus, A. M.-Edvv. (not found 

 elsewhere), Pontophilus gracilis, S. I. Smith (not found 

 elsewhere), Phoherus ccecus, A. M.-Edw. (? also in the Ara- 

 fura Sea), Uroptychus nitidus, A. M.-Edw. (not elsewhere). 



West Indies aud Mediterranean on the one hand, and in favour of a 

 former (Cretaceous and Eocene) open-sea connexion between Europe, 

 across the Sahara aud Arabia, far into India, on the other hand, is very 

 strong. My object here is simply to show how certain geological generali- 

 zations appear to be in some way confirmed by the zoological facts 

 recorded in this series of papers. 



