Introduction to Animal Morphology. 213 



capillaries on the intestine. The blood may be color- 

 less, with colored corpuscles (Glyceria, Phoronis, 

 Dujardiniae\ or more commonly is a yellow, green, 

 red, or blue serum with colorless corpuscles. The 

 color is often dissimilar in allied species. 



Respiration may take place by the surface, by the 

 water admitted into the perivisceral cavity, or by gills 

 which may be modified, filiform cirri, over or under 

 the parapodia, or dermal, ciliated, comb-like, pinnate 

 or branched processes, into which often pouches of 

 the body cavity enter, attached to the notopodia. In 

 the tube-dwellers there are long contractile threads in 

 bundles, or spirals, or fans, or tree-like, with a carti- 

 laginous axi> of support (Sabella). Some of these 

 cirri may lose their respiratory functions, become 

 club-like, and act as opercula to the tube. This 

 operculum may have a calcareous, terminal disc 

 (Serpula), or it may be dilated into a brood-pouch for 

 young (Spirorbis). In Fabricia, a temporary tube- 

 dwellcr, the operculum retrogrades into a simple 

 :acle. The gills contain either simple caocal divert i- 

 cula from the transverse communicating vessels, or 

 y may have separate inferent and efferent vessels, 

 nichus has eight oval, ciliated (respiratory ?) 

 laminae around the anus, and the lower end of the in- 

 LS also ciliated. In llcsione, air bubbles have 

 tnitted both by the mouth and anus. In 

 Syl I the pi-riudir taking in and xpulsion of 

 r from tin- inti-stiii*' has been notio-l. 



Dually a pair of symnn'- 

 uial ) or. 



I hese may br simple 

 mu< i Tubifcx, N,ii>, &C., ] \ 



