m OKHAMANDAL MARINE ZOOLOGY REPORT 



Part of the digestive gland and the superior branches of the aorta are indicated faintly- 

 through the thin non-muscular portion of the pallium adherent to the surface of the 

 visceral mass. Nat. size. 

 Fig. 20. Semi-diagrammatic view of one of the minute spherical cestode larvse found abundant in 

 P. placenta, seen in optical section, showing how asexual multiplication occurs by the 

 production of endogens. Only a single endogen {End) is here seen, but individuals 

 frequently contain several ; C.c, calcareous corpuscles. 

 „ 21. Advanced larva of Distomun placunce, n.sp., a trematode frequently found encysted in this 

 stage in Placunse from the Gulf of Kutch. 



PLATE IV. 



,, 22. Vertical transverse section across the body of a three months old individual (preserved in 

 formalin) about midway along the longitudinal axis. The section passes through the 

 anterior section of the stomach and along the axis of the internephridial passage. It passes 

 posterior to the parieto-splanchnic ganglion, and shows the relative position of the auricles 

 (Au.r and Au.l) to the nephridia {Neph.r and Neph.l), the manner in which the intestine 

 {Int) and the pyloric or crystalline style crecum (C.st.c) leave the stomach and the relation 

 of the distal region of the latter to the right mantle. X 16. 



„ 23. Slightly oblique horizontal section of a similar individual at the level of the cerebral ganglia 

 {Ger.g.l and Cer.g.r). Shows sections across stomach {St) ; last part of ascending region 

 of intestine {Int. 1) and initial part of descending intestine showing typhlosole {Int. 2) ; 

 labia {Lab) and upper edge of root of foot {F). x 20. 



,, 24. Horizontal section at the level of left auricle {Au.l), through ventricle (F.), showing auriculo- 

 ventricular valves ( V.a.v), right nephridial coecum {R.n.c), crystalline style {C.st), pedal 

 retractor muscle {Ret) ; also the direct efferent blood channel from the left branchise 

 to the heart by way of the common efferent branchial vessel {C.hr.eff) and left auricle 

 {Au.l). Xl6. 



„ 25. Transverse section through crystalline style sac (pyloric csecum) showing characteristic 

 uniformity in the length of the lining cilia {C.st.cil) and the concentric ringing which the 

 style shows in section. x 90. 

 26. Transverse section of second or descending section of intestine; showing form of typhlosole {ty). 

 XlOO. 



,, 27. Section from typical glandular region of nephridium to show renal cells. X 320. 



PLATE V. 



28. Vertical longitudinal section, a little to the left of the median line, through a three months old 

 Placuna. Shows the emergence of the pyloric ca?cuni (sac of crystalline style, C.st.c), also 

 pedal ganglion {Ped.g) below and close to the left cerebral ganglion {Cer.g.l). The section 

 cuts the internephridial passage transversely (/.n.^j) and shows the highly muscular 

 character of the ventricle (r). x 12. 

 29. Section of another individual cut in the same plane but well to right of the median line. 

 Shows the entrance into the stomach of some of the principal ducts of the digestive gland 

 {D.gl.d), the emergence of the intestine from the stomach, the continuity of the right 

 nephridium {Neph.r) with the right nephridial cfccum {R.n.c), the situation of the 

 accessory excretory organ {Acc.ex.o) at the most dorsal portion of the nephridium, and the 

 crystalline style sac dividing the right nephridium into two ventral lobes {Neph.r and 



