WITH NOTES ON THE WEST INDIAN SPECIES. 



325 



EXPLANATION OF PLATES XXVI— XXXII. 



The material was chiefly preserved in Mayer's Picro-Nitric solution and in a Chrome- 

 Osmic mixture which was recommended to me specially for preserving Enteropneusta by 

 Mr J. P. Hill. It gave excellent results and is the most reliable fluid for unique specimens. 

 The following proportions are employed : — ■ 



Chromic Acid l°/ o — 100 c.c. 

 Osmic Acid l°/ o — 2 c.c. 



Objects may be left in this fluid for 12 hours (overnight) and then washed out in water. 

 Specimens preserved in 4 — 5 °/ o formalin are useful for dissection. 



REFERENCE LETTERS. 



First gill-pouch. 



Coecum of gill-pouch. 



Gill-slit. 



First gill-slit. 



Pericardium (not in PI. XXVI. Fig. oA, q.v.) 



Hind-gut. 



Lm^tine. 



Inner circular muscles of collar. 



Intra-epidermal canal. 



Inner longitudinal muscles of collar. 



Hepatic saccule. 



Lateral gonad. 



Longitudinal muscles. 



Left proboscis pore. 



Lateral pouch of stomochord. 



Lateral septum. 



Lateral vessel. 



Medullary canal or cord (collar nerve-cord). 



Medial gonad. 



Median septum of proboscis. 



Outer circular muscles of collar. 



Oesophagus. 



Outer longitudinal muscles of collar. 



Proboscis coelom. 



Parabranchial ridge. 



Postbranchial canal. 



End-vesicle or end-sac of proboscis (Eichelpforte) 



Perihaemal cavity. 



Posterior neuropore. 



Peripharyngeal cavity. 



Post-trematic portion of end-sac (also pc). 



Pygochord. 



