DIPHASIA PINNATA. 255 



rises in the centre of the upper extremity, which is broad 

 and truncate, and produced at each side into a more or 

 less developed spine. They are often slightly furrowed 

 transversely. The male capsules form rows on the bran- 

 ches, partly overlapping one another. 



The female capsule is of much larger size, and presents 

 a complex internal structure, which has been minutely 

 described by Professor Allman*. It consists of two 

 chambers, the lower of which is traversed by the column 

 bearing the ovaries. This is surmounted by an upper 

 story, which encloses a marsupial sac, surrounded by a 

 number of branched ctecal tubes. The portion of the 

 capsule which forms a protective case for the marsupimn 

 is composed of three detached pieces that converge above. 

 The summit is pyramidal. After the liberation of the 

 embryos the top of the capsule presents a very ragged 

 appearance. 



D. tamarisca often attains a large size. 



Hab. On shells and stones from deep water. Though 

 not an abundant species, D. tamarisca is very widely dis- 

 tributed. It occurs in Ireland. 



[La Charente Inferieure, Bay of Biscay, common 

 (Beltremieux) : Grand Manan (Stimpson) : Massachusetts 

 Bay (Agassiz) .] 



6. D. PINNATA, Pallas. 



SERTULARIA PINNATA, Pallas, Blench. 136 ; Johnst. B. Z. 69, pi. xii. figs. 3, 4, 



and woodcuts, 69. figs, b, b. 



FUSCESCENS, Turt., Gmel. iv. 677; Lamx. Cor. flex. 195. 

 NIGELLASTRUM piNNATUM, Oken, Lelirb. Nat. 93. 

 DIPIIASIA PINNATA, Agass. N. H. U. S. iv. 355. 



SERTULARIA NIGRA (the female), Pall. Elench. 135 ; Johnst. B. Z. 68, pi. xii. 

 figs. 1 & 2, and woodcuts, 69. figs, a, a. 



* " Eeport on the Reproductive System in the Hydroida," British Assoc. 

 Report for 1863, pp. 373-4. 



