24ti s. GOTO. 



Plate XVIII. 



Fig. 1. Stage B/C. I^arva viewed tVoin the right. The broken line sliows the outline of 



the gut. X8H diam. 

 ,, "2. The same viewed from the left. X 80 diani. 

 „ o. Stage C/D. Larva viewed frojn the right. XSC) «liani. 

 „ 4. The same viewed from tlie left. x8(3 diam. 

 „ •"). Stage B/C. Selection from serial transverse sections, each section =7.0 a. There are 



70 sections in all ; and a is section 15, b section 20, c section "27, d section 43, the 



counting being made innn the posterior. x8(j diam. 

 „ (J. Stage B/C. Frontal section. x8C) diam. 

 „ 7. Stage C/D. Selection from serial transverse sections. Tliere are 90 sections in all ; 



a is section 14, 6 24, c 30, d 51. x86 diajii. 



Stage C/D. Frontal section. xSG diam. 



Stage C/D. From a frontal section; to show tiie formation of tlie mesentery leading 



to the formation of the epigastric enteroctel. X o'.)0 diam. 



Stage D. Selection from serial transverse sections. Tliere are 80 sections in all ; a 



is section 14, b 20, c ol, d 43, e 51. xSO diam. 



Stage E. Selection from serial transverse sections. Tliere are 00 sections in all ; a 



is section 12, b 17, c 38, d 43, e 47. 



Stage E. Selection from serial frontal sections. There are 70 sections in all, the 



jircoral lolie being left out; a is section 19, b 34, c 40, d 53, e 58. x80 diam. 



Stage E/F. Selection from serial frontal sections. There are 04 sections in all, tlie 



preoral lobe being left out; a is section 14, b 21, c 20, d 30, e 34, /42, r/ 40. X80 diam. 



Stage F. Selection from serial frontal sections. There are 79 sections in all ; a is 



section 10, b 21, c 23, d 25, e 29, / 32, (j 40, h 43, i 47, /: 54, I 50. x80 diam. 



Stage (t. Selection from serial frontal sections. There are 88 sections in all; a is 



section 30, b 43, c 51, d 01, c 08, / 73. x80 dia)ii. 



Stage F. From a fi'oulal section. The circular cntcrocu4 and Ihr ccnlral jjortiou 



of the pcriiiu'inal system still forms a single cavily (ent. dr.); the inesenchymatous 



portion of tlie perih;emal system is represented by a closed vesicle (j:e/v7(ce//(.). X390 



diam. 

 „ 17. Stage C/D. l'orliou of four successive transverse sections, to show the origin <if the 



"dorsal sac." X 140 diam. 



Abbreviations. 



mil. \ntirior cnterornl. p. s Left posterior enteroc<cl. 



call,, wj I'ore-cauai. p'.n' Secondary left posterior enleroctel. 



can- area Stone-canal. periirs Periœsophageal entcroccel. 



ent Enteron . periliaciu Perilipemal spaee. 



eii(. clr Circular eiileroeo-1. Hic. dor "Dorsal sac.'' 



epi'nas Epigastric entcrocul. sin. a/ Vxial sinus. 



Iiydr Ilydrocul. cas. ci'j ^Vater-vascular canal. 



p. d Bight posterior entcroeu'l. wt-s. a^. c/V.... Circular water-vascular canal. 



The Arabic nuini'i'als denote the prijuary hydrocicl [loiiciies. 



