JOURNAL OF MICROSCOPICAL SCIENCE. 



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I):BSCRIPTION OF PLATE XIII, 



Illustrating Professor Lankester's memoir " On Young 

 Stages of Limnocodiura and Geryonia." 



All the figures were drawn from the same embryo, in the living condition. 



Fig. 1 shows the velum («) retracted, so as to expose the surface of 

 prseumbral lid (c), with its central perforation {6). Eight tentacle* 

 are present, four per-radial (t*) and four adradial (i^) ; also two mat. 

 ginal bodies, one of which only (ot) is seen. 



Fig. 2. — Deep optical horizontal section of the same specimen, aUowing : 

 a. ectoderm of the abumbral surface ; I), the four radial canaU; 

 e. ectoderm of the manubrium; d. endoderm of the manubrium; 

 e. Striated muscular fibres. 



Fig. 3. — Similar view to that of Fig. 1, with the velum now expanded, so 

 that the free margins of its folds meet at the central region («), and 

 completely cover in the praeumbral lid. 



ot. marginal body (tentaculocyst). 



Figs. 4 — 5. — Two views of the velum in different conditions of con- 

 traction. 



a. free margin of the velum ; b. prseumbral lid ; ot. tentaculocyst. 

 Fig, 6.^Enlarged drawing of one of the two tentaculocysts. 



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