ON AMPHILINA PARAGONOPORA 8o 



Fig. 18 ( X cL'. 150). — Retracted proboscis in transverse section. 



Fig. 19 ( X cir. 310). — Portion of wall of proboscis in longitudinal section. 



Fig. 20 ( X cir. 2). — Diagram to illustrate the longitudinal extent of the 

 boring muscle of the proboscis. 



Fig. 21 ( X cir. 7). — ^Diagram to illustrate the distribution of the boring 

 muscle-fibres and the giant anchor-cells (Salensky's ' problematic cells '), 

 and the same structures shown in two transverse sections (a and b) at the 

 levels indicated. 



Figs. 22, 23 ( X cir. 300).— Giant anchor-cells with boring muscle 

 processes. 



Fig. 24 ( X cir. 300). — -Fibres of boring muscle. 



Fig. 25. — Diagram illustrating the connexion of the boring muscle-fibres 

 with the anchor-cells. 



Reference Letters in Figures 26-39. 



ANCC, giant ' anchor '-cell ; bc, ' braiii ' commissure ; bm, boring 

 muscle ; CALC, calcareous body : cut, cuticle ; ec4SH, egg-shell ; f, fila- 

 ment or tag on egg-shell ; gbl, giant blastomere ; GC, gland-cell ; hk,. 

 hooklet ; ICM, inner circular muscle-layer ; ilm, inner longitudinal muscle 

 layer ; inb, internal nerve branch ; ivm, investing membrane of larva ; 

 LLT, lateral longitudinal nerve-trunk ; Nn, nerve-fibre ; oblm, oblique 

 muscle-layer ; ocm, outer circular muscle-layer ; olm, outer longitudinal 

 muscle-layer ; par, parenchyma ; rtm, retractor muscle-fibres ; SUBC,. 

 subcuticula ; uo, opening of uterus ; YO, yolk material. 



Fig. 26 (X cir. 3.30). — ^Transverse section through body-wall of A. 

 paragonopora. 



Fig. 27 ( X cir. 330). — -Longitudinal section through body-wall. 



Fig. 28 ( X cir. 980). — -Early stage of growth of calcareous body. 



Fig. 29 ( X cir. 63). — Semi-diagrammatic figure of the anterior end of 

 the central nervous system. 



Fig. 30 ( X cir. 580). — -Eggs m commencement of uterus with shells and 

 yolk. 



Fig. 31 ( X cir. 580). — Morula stage of embryo surrounded by investing 

 membrane. 



Fig. 32 ( X cir. 580). — Early larva in longitudinal section showing one 

 large blastomere (shell not shown). 



Fig. 33 ( X cir. 580). — Section through posterior end of larva showing 

 formation of hooklet-cells. 



Fig. 34 ( X cir. 580). — Early larva in section showing gland-cells and 

 hooklet-cells. 



Fig. 35 ( X cir. 580). — Late larva seen in 02)tical section (the gland-cells 

 if present, were invisible). 



Fig. 36 (x cir. 980). — Hooklet from posterior end of larva. 



Fig. 37 ( X cir. 580). — Three of the degenerate larvae in shells, which 



G 2 



