Chap. IV. PARYPHA CROCEA. 249 



of the cells to which they are attached. These cilia are quite conspicuous, and, 

 in fact, may be seen through the walls of the stem, under favorable circumstances. 

 The horny sheath {Fig. 10, a) has the same finely laminated structure as that of 

 Tubularia. 



SECTION III 



PARYPHA CROCEA AG. 



Proles htjdroidea. Adult. — Parypha crocea grows in great luxuriance, attached to 

 floating timbers in Boston Harbor. Here, when the tide is low, the water is very 

 brackish, owing to the outflow of Charles River, and even when the tide is highest, 

 it is far from being pure sea- water. On this account, it may be said to be an 

 inhabitant of brackish water, especially as this Hydroid has never been found on 

 the open coast where there is pure sea-water. It seems to prefer only partial 

 sunshine, inasmuch as it is found most frequently, and in greatest luxuriance, on 

 the under side of the logs to which it is attached. It grows in bunches (PI. 

 23, Fig. 1), each bunch being the multiplied offspring, by budding, of a single 

 hydroid, and forming either a male or female colony. The stems are very much 

 contorted, irregularly branched, and densely intertwined at the base. From this 

 entangled mass the stem of each hydroid rises singly, to the height of from two 

 and a half to three and a half inches {Fig. 1"), and is terminated by a broad 

 and deep saucer-shaped head {d), which is surrounded by a coronet of slender, 

 uniserial tentacles, and has a long proboscis. The whole length of the stems is 

 enclosed in a horny sheath, which is wavy {Fig. 1*, a) or slightly nodose or 

 faintly ringed {b, c) at irregular distances ; but this cannot be readily perceived 

 except with a slightly magnifying power. 



The head of the hydroid is attached by the base of the saucer-shaped part 

 {Fig. 1", d) to a more or less globular expansion of the end of the stem {Fig. 

 V', c?'). From the edge of the saucer-shaped disk, or stomach, numerous slender 

 and gradually tapering tentacles (^') stand out in a single row, like fringes, with 

 their bases decurrent, on the under side of the head {Fig. 1", d), almost to its 

 base. At its bottom, the proboscis {p) is as broad as the disk, arising at the upper 

 side of the base of the tentacles, in the form of a convex cover to the saucer- 

 shaped stomach. From the centre of the latter a cylindrical, columnar portion {p), 

 about as thick as the stem, projects. This is, perhaps, more properly, to be called 

 the proboscis, inasmuch as it is very flexible and bears an active part, with the 

 tentacles {t) at its end, in catching the prey. It is strongly ribbed, by the decurrent 



VOL. IV. 32 



