THOEACIC GLANDS IN THE LABV^ OF TEICHOPTEBA- 



409 



consists of a single glandular tube, tlie inner part of which is 

 composed of large gland-cells, the terminal part being a thin 

 chitinous tube opening at the tip of a very long prominence 

 similar to that of Phryganea grandis, between the two pro- 

 thoracic legs. 



Fig. 2. — Limnophilus jlavieornis. 

 Prothoracic gland {g'^) with a part of cuticle bearing the plug-like organ {p). 



The meso- and metathoras contain no gland, and no trace of 

 a prominence is to be seen on their ventral face. 



The structure of the tubules is the same in all segments. The 

 glandular epithelium consists of a small number of large cells, 

 the central lumen being lined by a strong chitinous membrane. 

 This cuticle, or so-called intima, is quite smooth and entirely 

 devoid of pores or any kind of apertures through whicb the secre- 

 tory product could be supposed to flow out of the cells. The 

 presence of such a non-porous lining to a glandular tube is a 

 remarkable feature of these organs, though not an unknown 

 one amongst the Tracbeata. 



