1904.] NATURAL SCIENCES OF PHILADELPHIA. 755 



be found in the work of Vejdovsky (1894), particularly his fig. 17; this 

 represents an outline of the head of an immature individual, showing 

 at the tip of the definitive head the still persisting proboscis with a 

 transverse septum. The future head and trunk proper then lie behind 

 the proboscis of the larva, and this head-trunk becomes the complete 

 body of the adult; this we can say certainly, even though the early 

 post-larval development is entirely unknown. 



This head-trunk has a wall like the proboscis, a hypodermis with 

 cuticula, and longitudinal mesenchymatous muscle fibres. There is 

 no coelom, no peritoneum or mesenteries. The nervous system is 

 simply a ventral thickening of the hypodermis. In the head-trunk 

 is found the second striking peculiarity of the Paragordius larva — a 

 gland connecting by a long duct with the anterior end of the proboscis. 

 This gland is entodermal, arising as an abstriction from the anterior 

 end of the entodermal tube. In point of origin it resembles an entero- 

 coel, a mesoderm sack, and its early lumen is a portion of the gastroccel. 

 But there the resemblance ceases, for it becomes a gland, evidently 

 secretory and not excretory, which later develops a duct to the exterior. 

 Its origin is unpaired. The only forms which show a similar unpaired 

 enteroccfil arising from the anterior end of the entoderm tube are the 

 Holothurians, and there an outgrowth of a portion (hydrocoel) of the 

 hydro-enterocoel connects it, in the form of the stone canal, with the 

 exterior. But it would be a rash comparison, in no Avay justified, 

 between a Gordiacean and a Holothurian. This gland probably 

 continues to a late stage of the development under the form of the 

 "braune Driise" of Gordius, described by Vejdovsky, but is not 

 homologous with the problematical ''supraintestinal organ" that I 

 found in the adult of Paragordius. 



When we consider this ectodermal proboscis, the cctodermic dia- 

 phragm and the enterocoelic gland; the absence of any coelomic 

 cavities, ciliary wreaths and excretory organs; the lack of a mouth 

 and the mesenchymatous musculature, we must conclude this union of 

 characters to make the Gordiacean larva unique, not closely comparable 

 with any other larva. 



If my interpretation of the larva is correct, then the early post-larval 

 development, which has yet to be studied, should show the mouth 

 arising in the plane of the diaphragm, probably as an ectodermic 

 stomodseum; the dorsal commissure of the brain developing in the 

 same region; and the reproductive organs arising from the small 

 mass of mesenchym cells at the posterior end. But the point of most 

 importance that remains to be investigated is the first origin of that 



