{M16. Cambridge Philosophical Society : — 



of climate, the MytUus edulis being found as abundantly on the coast 

 of Greenland as on our own shores. 



It is not difficult to account for the presence of the southern species 

 on the coast of Norwaj% as the Gulf-stream sets directly along the 

 coast, warming its waters, and rendering them habitable for species 

 requiring a moderately high temperature. The great abundance and 

 wide distribution of these species show that the present order of 

 things has continued for a great length of time. The gradual ex- 

 tinction of northern shells on our coasts is still going on ; the 

 number of living specimens of Pecten danicus is very small, while 

 dead shells are very abundant, and fresh dead specimens of Pecten 

 islandkus are frequently dredged, though a living specimen has not 

 yet occurred. It is probable that tliis species has died out very 

 recently. 



On the eastern shores of Davis's Straits the Mollusca are about 

 half as numerous as on the coast of Norway. The fauna differs in 

 the prevalence of arctic types and the total absence of southern. At 

 a former period the fauna was of a mixed character ; species now in- 

 habiting more southern latitudes are found fossil in the raised beaches 

 at Disco Island, which species are no longer found living on the coasts. 



Nov. 6. — A paper was read by Dr. Donaldson " On the Structure 

 of the Athenian Trireme, considered with reference to certain diffi- 

 culties of Interpretation." 



The author's intention was to show in this paper that the arrange- 

 ments for seating the three tiers of rowers in the trireme, which Dr. 

 Arnold has called " an indiscoverable problem," may be adequately 

 explained by an examination of the terms which are used to discri- 

 minate the rowers, and of other words referring to the different parts 

 of the war-galley. The name of the zygitce, or rowers of the middle 

 tier, implies that they sat on the l^vya, or transverse planks connect- 

 ing the opposite sides of the vessel, also called aeXfjara, and in 

 earlier times kXtjI^es. The thalamitee, or rowers of the lowest tier, 

 must, in accordance with their name, have had their seats attached 

 to the ribs of the vessel in the 6d\af^os, or hold. And the thranita, 

 or rowers of the highest tier, sat on Opijvves, or benches like low 

 stools, extending for seven feet along the alternate ^vya. The ej)i- 

 batce, or marines, whether as working the supernumerary oars, or 

 as fighting, occupied platforms running along the bulwarks. This 

 view of the matter explained the fact that there was a gangway 

 from the stern to the prow for the passage of the officers, &c. along 

 the aiX/^ara or i^vyci, between the ends of the stools on which the 

 thranitae sat. This gangway was called the (reXis, and the same 

 name was given to the passages leading down to the orchestra from 

 the upper part of the theatre between the rows of seats occupied by 

 the spectators. Hence was derived a philological explanation of the 

 words in Aristoph. Equites, 546 : — 



aipeixb' avT(p ttoXv to podiof, irapaTrejjtpur' k(f evSeica Kwirais 

 Oopvftoy j^prioTOV XrjyuiTtji'' 

 for there were eleven tiers of seats between each diazoma of the 



