PROCEEDINGS 



THE ROYAL IRISH ACADEMY. 



1843. No. 42. 



November 13. 



SIR Wm. R. HAMILTON, LL.D., President, in the Chair. 



Dr. Allman drew the attention of the Academy to cer- 

 tain undescribed pecuHarities in the anatomy of Anthoce- 

 phalus, a genus of Entozoal worms. The points especially 

 dwelt upon by Dr. Allman were the remarkably definite ar- 

 rangement of the hooks with which the proboscides are fur- 

 nished, and the singular apparatus destined to effect the 

 retraction and exsertion of the latter organs. The probos- 

 cides were described as communicating each with a distinct 

 tube, which extending through the entire length of the ani- 

 mal, terminates posteriorly in an oval dilatation, with thick- 

 ened walls. The retraction of the proboscides consists in 

 an inversion, by which they become invaginated in the tu- 

 bular appendage. This invagination is effected by means of 

 a muscular filament, which is attached by one extremity to 

 the internal surface of the eul de sac of the proboscis, and 

 may be thence traced through the tube as far as the oval 

 body in which the latter terminates. 



The mode by which the exsertion of the proboscides is 

 effected would appear to be as follows : — These organs, 

 together with their tubular prolongation through the ver- 

 micular body of the Entozoon, are filled with a transparent 

 fluid, which during the inversion of the proboscides is ex- 



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