SABELLIFORMI A 339 



(beyond the neuropodial chaetae) and nearly encircle the body. 

 The animal is 4 or 5 inches long, dull green, with purplish gills. 

 Between tide-marks. North Sea and Mediterranean. 



Amphiglena mediterranea Leyd. is only about inch long, 

 hermaphrodite, and has eyes on the peristomium and on the anal 

 segment. It is a very elegant little worm, and as a living object 

 under the microscope, with the cilia on the gills, is very beautiful. 

 The gills consist of six filaments on each side, provided with the 

 usual double row of ciliated processes. 



FAM. 3. Amphicorinidae. Small hermaphrodite Sabellids in 

 which each gill tuft contains only a few branching filaments. 

 The simplest form is Haplobranchus aestuarinus Bourne, 1 which 

 occurs in the rather foul mud at low tide in the estuaries of the 

 Thames, the Liffey, and other rivers. The animal is about 

 inch long, with four finger-shaped processes on each side, and a 

 pair of larger, vascular processes on the ventral surface. These 

 five branches are gills (palps), although, owing to the small size of 

 the worm and simple vascular system, the four lateral filaments 

 have no blood-vessels. The animal consists of only eleven 

 chaetigerous segments, and lives in a tube made of mud particles. 2 

 Fabricia sabella Ehrenb. (Amphicora fdbricia Mull.) has three 

 gills on each side, each with a number of secondary branches of 

 different sizes, but so arranged as all to reach the same level. It 

 has eyes in its tail and swims backwards. 



FAM. 4. Serpulidae. The thorax is provided with an un- 

 dulated membrane on each side, chiefly employed in smoothing 

 the inside of the tube ; it represents the dorsal and ventral 

 cirri of these segments. The gland shields are confined to the 

 thoracic segments. In many genera the dorsalmost gill fila- 

 ment on one or both sides is terminally dilated and serves as an 

 operculum. The tube is calcareous, and attached to rocks, shells, 

 etc., for a greater or smaller part of its extent. 



Serpula vermicularis L. forms a pinkish tapering tube about 

 3 inches long ; the narrower fixed end is coiled. It is marked 

 at irregular intervals with encircling ridges, indicating cessation 



1 A. G. Bourne, Quart. J. Micr. Sci. xxiii. 1883, p. 168. 



2 Closely allied is Manayunkia Leidy, which occurs in fresh-water lakes of 

 America. Another fresh-water genus is Coabangia Giard, which perhaps deserves 

 the creation of a special family. The anus is ventral and anterior. The chaetae are 

 peculiarly arranged, dorsal uncini being present only on four segments. The first 

 body segment carries a ventral bundle of five great " palmate " chaetae. 



