1907.] 



NATURAL SCIENCES OF PHrLADELPHIA. 



141 



KXI'LAXATIOX OF PlaTES XII AND XIII. 



The figures have been drawn by the aid of the camera hicida at the 

 level of the table, under Zeiss homo. imm. tV; using the oculars 2 and 4 

 of Zeiss, and 3 and 5 of Leitz. The magnification, in diameters, of each 

 of these combinations was determined, and the particular magnification 

 employed in each figure is indicated after ,the description of that figure. 



Reference LEirTESg. 



fiin.c, amoeboid cell. 



br., brain. 



6r.com., transverse commissure of brain. 



c.com., circumoesophageal commi.^sure. 



c.e.n., central (anterior) end of ne- 

 pliridium. 



e.g., cilia of ciliated groove. 



c.gl., cephalic gland. 



c.gl.d., duct of cephalic gland. 



c.r. 1-9, 1st to 9tli ciliated rings. 



cut., cuticle. 



d.c.n., diagonal canal of nephridium of 

 1st pair. 



d.l.rn., dorso-lateral longitudinal mus- 

 cle. 



d.n., duct of nephridium of 1st pair. 



d.v.m., dorso-ventral muscle of head. 



€., eye. 



g.c, ganglion cells. 



g.gl., gastric gland. 



g. 2-5, ganglia of the 2d to the 5th 

 trunk segments. 



gl. 1-3, hypodermal glands of the 1st, to 

 the 3d type. 



hyj)., hypodermis. 



i.c.n., inner (anterior) canal of ne- 

 phridium of 1st pair. 



i.l.. inner lip. 



int., intestine. 



int.m., muscle encircling, terminal por- 

 tion of intestine — spliincter ani. 



/., lens of eye. 



l.g.n., lateral glandular portion of 

 nephridium of 1st pair. 



l.m.c, transverse muscles of head. 



l.m.f., longitudinal muscle fibres. 



l.m.i., insertion of longitudinal nmscles. 



l.n., lateral nerve cord. 



in., mouth. 



men., megenchymatous tissue. 



vi.n., nerve to ventro-lateral longi- 

 tudinal muscle. 



n., nucleus. 



n./., nerve fibres. 



np., neuropil. 



(Bs., oesophagus. 



ces.m., esophageal muscles. 



ces.n., CBsophageal nerve. 



Q.l , outer Up. 



ooc, ooC5f,tes. 



oog., oogonia. 



p.c, pigment of eye. 



per., peritoneum. 



pr.com., preoral commissure. 



pro. 1, anterior epithelial portion of pro- 

 boscis. 



pro. 2, posterior muscular portion of 

 proboscis. 



pro.f., flexor of proboscis. 



pro.l., levator of proboscis. 



pro.pr., protractor of proboscis. 



pro.r., retractor of proboscis. 



r.b., refringent body. 



s.gl., salivary glands. 



s.gl.d., duct of salivary glands. 



St., stomach. 



st.m., stomach wall. 



t.c.n., transverse canal of nephridium 

 of 1st pair. 



t.cil., tactile cilia. 



t.com., transverse commissure. 



v.g.n., ventral glandular portion of 



nephridium of 1st pair. 

 v.l.m. 1, median ventral longitudinal 



muscle. 

 v.l.m. 2, ventro-lateral longitudinal 

 muscle. 



Plate XII, Fig. 1. — The nervous .system, sHghtly schematized, and represented 

 as seen from the dorsal side. Reconstructed from a series of 102 sec- 

 tions of a single individual. The outlines of the body, the mouth, and 

 the ciliated bands are also reprasented. X 4.50. 

 .Fig. 2. — Cross section through the bruin, showing the neuropil, ganglion 

 cells, and eves. X 665. 



