358 SUMMARY OF CURRENT RESEARCHES RELATING TO 



swellings on all sides from which the polyp-tubes originate. (The name 

 Sacculina is surely appropriated for a familiar parasitic Crustacean.) 

 Descriptions are given of Ophiodes australis sp. n. and Aglaophenia 

 lakeri sp. n., and notes on many species of Phimularia and other 

 genera. The Australian species of Hydra are also discussed. J. A. T. 



Growth of Coral Reefs. — A. G. Mayer {Year Book Ccmugk 

 Institution, 1918, 17, 168-70). On the upper surface of a Samoan 

 reef-flat, measuring 2,550,000 square feet, a computation was made 

 of the number of heads of Pontes, Acropora, Focillopora, Psammocora, 

 and Pavona, and of their growth in a year. They appear to add about 

 805,000 lb. of limestone each year to the upper surface, and other 

 genera will raise the amount to 847,000 lb. On the minus side must 

 be reckoned the loss due to the wash of the breakers (100,000 lb.), to 

 solution by Holothurians (2,900,000 lb.), and to other destructive 

 agencies. As the reef-flat grows outward the shorewards parts are 

 destroyed, and the reef -flat appears to be deepening at present, though 

 the average depth of water over it at low spring tide is less than twelve 

 inches. This does not mean that a fringing reef must necessarily 

 change into a barrier reef, for " as the reef -flat deepens the factors 

 which destroy ' it probably diminish and a balance may be attained 

 between the accession of limestone due to growth of corals and other 

 organisms and its loss due to mechanical and organic causes." Mayer 

 finds that the Samoan corals grow fully twice as fast as do those of 

 Florida and the Bahamas according to Vaughan. This is probably due 

 to the better food supply in the Pacific. J. A. T. 



Corals of Pacific Coast of Canada.— S. J. Hickson {Bionomical 

 Leaflets, McGill University, Montreal, 1917, 6, 21-4). The fauna of 

 the coast from Puget Sound to Alaska is relatively little known. Atten- 

 tion is called to two Peiinatulids : Osteocella septeMrionalis Gray, a long 

 fleshy sea-pen, with a skeletal rod of bone-like hardness ; Leioptihim 

 qiiadrangulare (MorofP), with kidney-shaped pinnules and marginal 

 teeth on the calices ; to five Alcyonarians, Paragorgia arborea (Linn.), 

 which also occurs off Norway ; Primnoa U'illeyi Hickson, also circum- 

 polar ; Caligorgia fraseri Hickson ; Psammogorgia teres Verrill ; and 

 Clavidaria moreshii Hickson. Reference is also made to Stylaster 

 norvegicus Gunnerus and to two Madreporarians — namely, Balanophyllia 

 eJegans and Paracyathus caltha. J. A. T. 



Respiration Rates of Samoan Alcyonarians.— Lewis R. Gary 

 {Year Boole, Carnegie Inst., Washington, 1918, 17, 164-5). In 

 Akyonium flexile there was a consumption of 82 "8 c.c. Oo per kilogram 

 of fresh weight per hour; in Lobophytmn conjertum, 55*424; in 

 Lobophytum rigidum, 42*4; in Sarcophytnm glauciim, 21*3. In the 

 last the spicule content is only about 6 p.c. ; in the species of Lobo- 

 phytimi it is near 20 p.c. ; so that the oxygen consumption in the latter 

 would appear much greater. But in Akyonium flexile the proportion of 

 spicules is only slightly greater than that in Sarcophytnm, so the 

 explanation of the differences in terms of spicule percentage is inade- 

 quate. The author notes that at Tortugas he observed that the species 



