112 Proceedings of the Royal Society of Victoria. 



staining ground substance, resembling closely the ground 

 substance of the mesoderm in Coelenterata, in which various 

 kinds of cells are imbedded. The most characteristic of the 

 imbedded cells are small, irregularly shaped, finely granular, 

 nucleated masses of protoplasm (Fig. 24, gr. c.) which either 

 occur singly or in irregular groups resen:ibling syncytia. 

 These cells are very abundant above and at the sides of the 

 proboscis sheath and also below the alimentary canal, their 

 appearance suggests that they may be amoeboid l;>ut this of 

 course requires proof. 



We also find numei'ous cells greatly elongated so as to 

 form delicate fibres, but with the nucleus still clearly visible 

 in the middle. These ar'e readily distinguishable in the 

 region between the proboscis sheath and alimentary canal, 

 where the gelatinous-looking ground substance is very 

 strongly developed and contains compai-atively few cells. 

 Frequently these cells branch, and I believe they form 

 networks like the stellate mesodermal cells of sponges, 

 which they closely resemble. 



Occasionally the gelatin(jus-looking ground substance 

 appear-s to be replaced by a close netvvoi-k of very delicate, 

 non-nucleated, transpa.reirt fibrils, but this I am inclined to 

 regard as a post-mortem condition due to the method of 

 prepai'ation. 



We may mention in this place certain structures wdiich 

 occur imbedded in the ground-substance and which we have 

 not yet had occasion to refer to. 



(I) The Cephalic Gland (i^'ig. 7, c. gl). — This consists of a 

 curious mass situated in the head region dorsally and laterally, 

 overlying the proboscis sheath and doi'sal lobes of the ganglia, 

 inside the layer of longitudinal muscles. It consists of a number 

 of large, irregular, granular masses, closely packed together. 

 Each mass appears to be -made up of a large number of small 

 cells, for each contains numerous small 'luclei and sometimes 

 cell divisions can be clearly distinguished. The cephalic gland 

 stains deeply with hsematoxylin but onlj- slightly (except 

 the small rruclei) with borax carmine and aci<l alcohol. 1 

 have not been able to make out any definite ducts leadiirg 

 to the exterior, but the appearance of my .sections leads 

 me to believe that the secretiorr is passed out through 

 extemporised channels ovci the back and sides of the head. 



Gulliver describes* and figuies a " cephalic glandular 



* Philosophical Transactious of the Koyal Society of Loudon, Vol. 168, 

 1879, p. 557, et scq, Plate LV. 



