286 E. W. MAOBBIDE. 



Figs. 44— 46.^Three sections of a larva of Stage D. Fig. 44 shows the 

 opening of the pore-canal into anterior coelom ; Fig. 45, opening of the stone- 

 canal into the same ; and Fig. 46, the opening of the stone-canal into the 

 hydrocoele. It shows also that the hydrocoele has a wide opening into the 

 anterior ccelom independent of the stone-canal. 



Fig. 47. — Sagittal section of a larva of Stage D, to show the relations of 

 the lobes of the left hydrocoele to each other. 



Figs. 48 — 50. — Three sections of a larva of Stage B. The larva has suffered 

 an injury, a piece of ectoderm in the prseoral lobe indicated by the dotted line 

 being missing. Fig. 48 shows relation of rudiment of oral coelom {or. c.) to 

 the right dorsal horn of left posterior coelom (_l"p"c",). Fig. 50 shows the 

 great growth of the left hydrocoele (compare Fig. 40). a. ee. Adult oesophagus ; 

 rudiment of the "stomach" of the adult. In Fig. 49 the o of or. e. has failed 

 to print. 



Figs. 51—63. — Three sections of a larva slightly older than the preceding, 

 to show rudiments of the perihsemal spaces {ph.). These are numbered ac- 

 cording to the lobes of the hydrocoele between which they occur: ph. 1.3, 

 ph. 2.3, ph. 3.4, and ph. 4.5. ph. 1.2 arises from the anterior coelom, the 

 rest from the left posterior ccelom. The lobes of the hydrocoele are com- 

 mencing to be trifld. 



PLATE XIY. 



The same remarks apply to this plate as to the two foregoing. 



Figs. 54 — 57. — Four sections of a larva about midway between Stages E 

 and F. Fig. 54 shows the incipient dorsal constriction of the anterior coelom 

 into a stalk portion {a.) and a body portion or axial sinus («'.) ; also the origin 

 of the perihsemal rudiment {ph. 1.2) from the anterior coelom. Fig. 55 shows 

 the growing tip of the right ventral horn of the left posterior coelom, and over 

 it the arm rudiment No. V ; it shows also the stone-canal opening into the 

 hydrocoele and the perihsemal rudiment insinuating itself between the hydrocoele 

 and the ectoderm. Fig. 66 shows the axial sinus and the stalk coelom con- 

 tinuous with each other, and also the anterior coelom opening into the right 

 ventral horn of the left posterior coelom. Fig. 57 shows that this right ventral 

 horn is commencing to be again divided from the anterior coelom ventrally 

 by the outgrowth of a septum. 



Figs. 58 and 59. — Two sections of a larva slightly older than the preceding, 

 to show the separation of the axial sinus ventrally on the one hand from the 

 stalk ccelom, and on the other hand from the hydrocoele. Py. Rudiment of 

 the pyloric sac of adult. Ice. Last trace of the larval oesophagus. 



Fig. 60. — Section of larva about the same age as preceding, to show the 

 fifth perihsemal rudiment {ph. 51) which intervenes between lobes 5 and 1, 

 as yet widely separated. 



