SPONGES, ZOOPHYTES, AND SEA-FIRS. 53 



beginner it may seem that the sea-firs are less interesting 

 than some of the more "lively" of the shore animals, 

 we shall rapidly review all the more important families, 

 partly because they afford most interesting examples of 

 progressive evolution, and partly because the study of 

 them constitutes an admirable training in minute accuracy 

 of observation. A wet evening spent over a handful of 

 sea-firs, studied with the aid of the low powers of the 

 microscope or a good lens, will be found of great value 

 to anyone at all interested in species work. 



A very insignificant little sea-fir Opercularella lacerata 

 may serve to indicate the characters of the family Campa- 

 nulinidse, which represents the process of transition from 

 the Campanularian condition to that found in other families. 

 This sea-fir has stalked cups, but they are not bell-shaped, 

 but ovate and conical, while the zooids are cylindrical with 

 a short proboscis. A special peculiarity is that the cups can 

 be closed by an elaborate lid, or operculum. 



The next stage in the transition from the Campanularian 

 condition is seen in the family Lafoeidae, where the cups are 

 tubular and almost without a stalk (sessile). The only 

 example we shall consider is Lafoea dumosa, which occurs 

 both on the shore and in deep water. It may reach a 

 height of four inches, and is then erect and irregularly 

 branched, but the specimens found between tide-marks are 

 usually small and have simple creeping stems. The tubular 

 cups are very numerous and spring from all sides of the 

 stem. The whole colony has a yellowish tint. 



One other small transitional family must be mentioned, 

 which includes the curious "herring-bone coral," a species 

 often cast up on the beach, and occasionally found between 

 tide-marks. The whole colony is figured on page 319. It 

 is a large form, sometimes reaching a height of ten inches, 

 and is peculiarly stiff and rigid, differing in this respect 

 from the majority of the plant-like sea-firs. The Latin 

 name of this form is Halecium halecinum, and it belongs to 

 the family Haleciidse. The special peculiarity is that the 

 cups are sessile, and are placed in two rows on the stem (see 

 Fig. 19). This recalls the conditions seen in the next 

 family, the Sertularians ; but there the cups are let into 

 the stem, while those of Halecium are placed on a project- 



