162 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 



tral face of the median anterior lobe. Other smaller vessels enter the 

 ventral face of the gland at several points, coming from the trunks sup- 

 plying the tissues upon which the gland rests. 



To summarize, the lateral part of the labyrinth, together with all the 

 endsac, is supplied by the antenna! artery, while the median part — 

 except the tip of the median anterior lobe — is supplied from the sternal 

 artery. 



The nerve supply of the gland is from the nerve trunk running to the 

 second antenna. Immediately after this trunk emerges from the super- 

 cesophageal ganglion, it gives off a branch which passes outward and 

 backward to enter the median anterior lobe of the gland. The point of 

 entrance is on the ventral face near the median edge. The nerve trunk 

 to the second antenna also sends several small branches into the edge of 

 the median anterior lobe ; these arise at points more distal than that at 

 which the main branch arises. I have not found any nerve branches 

 entering at the hilus, nor in the posterior region in a position correspond- 

 ing to the blood supply from the sternal artery. 



B. Finer Anatomy. 



The gland proper consists of two distinct parts. The relation of the 

 two parts — the endsac (sac. trm.) and the labyrinth (Ihy.) — is seen in 

 Figure 2 (Plate 1), which is a transverse section of the gland proper 

 about half a millimetre posterior to the bottom of the hilus. The end- 

 sac is dorsal to and covers the whole of the labyrinth except its extreme 

 edges. Its average dorso-ventral depth at this region is about one 

 fourth that of the labyrinth. This ratio is greater than the average for 

 the whole gland. 



The endsac shows a considerable regularity in the arrangement of its 

 cavities. At the bottom of the hilus there is a single large chamber of 

 irregular sliape, from which outpocketings radiate. These are separated 

 from one another by folds of the wall of the endsac, which form complete 

 septa. These outpocketings branch dichotomously many times, and thus 

 produce a system of compartments which become smaller and smaller 

 until the edge of the endsac is reached. In these compartments there 

 are secondary foldings of the wall forming incomplete septa, which are 

 more frequent on the ventral than on the dorsal wall of the compart- 

 ments. In Figure 2 (Plate 1) tlie compartments near the edge of the 

 endsac arc cut crosswise ; those near the centre, lengthwise or diagonally. 



The dorsal face of the endsac lias attached to it the closely adhering 

 ventral wall (par. vs., Figure 2, Plate 1) of the overlying vesicle. This 



