294 NATURAL HISTORY SOCIETY OF DUBLIN. 



cimen before you. The specific name porrigens has been given from 

 its capability of being stretched, which, from its wrinkled appearance 

 in the intestine, it well deserves. Sometimes half the length of the 

 entozoon was concealed in the tubular cavity, which was generally an 

 inch long. The Echinorhynchus porrigens inay be described as con- 

 sisting of three distinct parts — the head or receptacle, the neck, and 

 elongated body. We shall merely direct your attention this evening 

 to the first, an enlarged diagram of which is before you. It consists 

 of a fleshy body of a double conical form, very wide at its thickest 

 base in proportion to its length ; from one of the truncated apices 

 of which protrudes a conical, nearly cylindrical, proboscis, armed 

 with an array of hooks, as you will see in the microscope. We have 

 reckoned about twelve rows, each row consisting of ten or twelve 

 hooks, set obliquely so as to effect a spiral arrangement. They are 

 hollow at their base ; and the lower rows are imperfect, or not de- 

 veloped in growth. This formidable proboscis is retractile, and it 

 is generally found in a retracted state. Rudolphi states that he 

 was not able to effect its protrusion ; we, however, did not find 

 much difficulty. From its armature and shape one might suppose that 

 in retraction and protrusion it was turned inside out, like the finger of 

 a glove ; but we have seen specimens half protruded, and they were 

 not reversed, but drawn directly within a circular muscular collar. 

 This proboscis is retracted by longitudinal bands of muscles situated in 

 the receptacle, which also contains other important organs, which it 

 would be tedious to dwell upon in this abstract. The neck is very 

 thin, and at its commencement smoother than the body, with which it 

 is continuous, without abrupt termination. The body is very deeply 

 wrinkled, these becoming more transverse towards its truncated extre- 

 mity, where it undergoes a slight constriction. 



A paper was then read — 



On the Anatomy of Ascaris (Atractis) dactyluris (Rud.). By Alex- 

 ander Macalister, L. R. C. S. I., F. R. GK S. I. 



As the attention of the members of the Natural History Society of 

 Dublin has been of late directed to the consideration of the group of 

 Entozoa, I think it might not be uninteresting to communicate a few 

 anatomical facts with regard to the structure of a species of intestinal 

 worm, which has lately fallen under my observation. While engaged 

 in examining the anatomy of Testuclo Grceca, I was surprised to find 

 that the alimentary canal in all the individuals which I dissected was 

 filled with worms in large quantities ; in fact, that Entozoa constituted 

 more than half of their contents. Of these there were several 

 species; but that which was most numerous was the small, white, 

 usually straight, somewhat shuttle- shaped Ascaris dactylurus, first 

 discovered by Bremser, and named by Rudolphi. The species is de- 



