476 



INVERTEBRATE MORPHOLOOT. 



Beneath the thin cuticle is situated the hypodermis, and 



beneath this a well-developed 

 dermal muscular system re- 

 calling that of the Annelida, 

 being composed of an outer 

 layer of circular muscles, be- 

 low which are diagonal fibres, 

 and below these again strongly- 

 developed longitudinal muscles 

 arranged in bundles, two of 

 which are situated dorsally, 

 two laterally, and three ven- 

 trally. In addition to these, 

 dorso - ventral bands occur 

 passing across the coelom and 

 dividing it into three chambers, 

 one median and two lateral, 

 and special muscles are also 

 present for moving the limbs. 



The coelom is tolerably 

 capacious and consists of two 

 portions. The larger portion 

 is divided by partitions into 

 several subordinate cavities 

 (Fig. 220), and is lined through- 

 out by a peritoneal epithelium 

 which covers the various or- 

 gans. From it are, however, 

 d = iDtestine. separated certain cavities with 



go = opening of reproductive orgau. definite walls, which stand in 

 o = ovary. relation to the nephridia and 



the reproductive organs and 

 will be spoken of in connection 

 with these organs. A heart 

 (Fig. 220, li) of a tubular form 

 extends throughout almost the 

 entire length of the body, lying 

 in a pericardial space (Fig. 220, pc) incompletely separated 

 from the rest of the coelom by a fenestrated transverse par- 



FiG. 219. — Figure showing the 

 Stktjcturb of a Fbmalb Peripatus 

 (from Hertwig). 

 a = anus. 



at = antennae. 



bm = ventral nerve-cord. 



og = brain. 



p = pbarynx. 

 sd ='slime-glands. 



so = nephridia. 



sp — salivary glands. 



ir = tracbeae. 



u = uterus. 



