2 86 COELENTERATA HYDROZOA chap. 



In Errina the pores are sometimes irregularly scattered, but 

 in E. glahra they are arranged in rows on the sides of the 

 branches, while in E. ramosa the gastropores occur at the angles 

 of the branches only. The dactylopores are situated on nariform 

 projections of the corallum. The ampullae are prominent. There 

 are several gonophores in each ampulla of the male, but only one 

 in each ampulla of the female. This genus is very widely distri- 

 buted in water from 100 to 500 fathoms in depth. 



Phcdangopora differs from Errina in the absence of a style in 

 the gastropore ; Mauritius. — Pliohothrus has also no style in the 

 gastropore, and is found in 100-600 ftithoms of water off the 

 American Atlantic shores. 



Distichoiiora is an important genus, which is found in nearly 

 all the shallow seas of the tropical and semi-tropical parts of the 

 world, and may even flourish in rock pools between tide marks. 

 It is nearly always brightly coloured — purple, violet, pale brown, 

 or rose red. The colony usually forms a small flabellum, with 

 anastomosing branches, and the pores are arranged in three rows, 

 a middle row of gastropores and two lateral rows of dactylopores 

 on the sides of the branches. There is a long style in each 

 gastropore. The ampullae are numerous and prominent, 

 situated on the anterior and posterior faces of the branches. 

 Each ampulla contains a single gonophore in the female colony 

 and two or three gonophores in the male colony. 



Spinipora is a rare genus from off the Eio de la Plata in 

 600 fathoms. The branches are covered with blunt spines. 

 These spines have a short gutter-like groove at the apex, which 

 leads into a dactylopore. The gastropores are provided with a 

 style and are situated between the spines. 



Steganopora^ from the Djilolo Passage, in about 600 fathoms, 

 is very similar to Sjnnijwi'a as regards external features, but 

 differs from it in the absence of styles in the gastropores, and in 

 the wide communications between the gastropores and dactylopores. 



Stylaster is the largest and most widely distributed genus 

 of the family, and exhibits a consideral^le range of structure in 

 the many species it contains. It is found in all the warmer seas 

 of the world, living between tide marks at a few fathoms, 

 and extending to depths of 600 fathoms. Many specimens, but 

 especially those from very shallow water, are of a lieautiful rose 

 1 S. J. Hicksou anrl H. England. Siho<ia Expcd. viii. 1904, p. 26. 



