1885.] GLANDS OF MYGALE. 5 



third lobes are shorter, thicker, and directed transversely ; they 

 extend slightly beyond the edges of the entosteriiite, and descend a 

 little way into tlie coxae of the fourth and fifth appendages. 



In addition to these four coxal prolongations, the gland has again 

 two internal projections near its middle third. These projections 

 correspond to two slight excavations of the entosternite, between its 

 lower plate and its upper prolongations. The latter pass above 

 the gland between its coxal lobes, so that only the extremities of 

 these can be seen between the prolongations of the entosternite. 



The annular stomach, which rests on the entosternite, sends its 

 lateral diverticula between these superior prolongations. The four 

 posterior diverticula of the stomach ' pass above the lobes of the 

 coxal gland, are then bent back, and |)ass between the muscles of 

 the corresponding coxse,^ and extend below the cepalothoracic 

 ganglion. 



The colour of the gland is uniform, a brownish yellow not unlike 

 that of the stomach and its lateral diverticula. Its appearance is 

 coarsely cellular, siiowing distinctly the groups of cells of which it is 

 made up. 



I have nowhere seen any efferent duct, either passing to the 

 exterior, or to any internal organ. The gland in Mygale, like that 

 of the adult Limidus and Scorpio, is therefore a closed gland. 



The shape and position of the coxal gland, as I have observed 

 them in this large South-American Mygale, do not represent an 

 isolated fact or one peculiar to this species alone. The diagram 

 Plate II. fig. 2 shows in fact that in Mi/gale cceinentaria, and con- 

 sequently in all the Tetrapneumones, the relations of the gland are 

 almost completely identical^. 



When it is possible to study fresh specimens of Limulus, Scorpio, 

 and Mygale, 1 think it would be useful to examine the contents 

 of the gland from the chemical point of view. The result of such 

 an examination would certainly help to determine the ]jhysiological 

 function of this curious organ ^. 



EXPLANATION OF PLATE II. 



Fig. 1. Diagram of a transverse section of the ceplialothorax of Myffale coemen- 

 iuria, Latr. (X9), passing through the coxa- of the third pair of am- 

 bulatory legs, and showing the relations of the right coxal gland («) 

 with the entosternite (A') and the digestive apparatus ; d, lateral 



1 In addition to the four large pairs of lateral divei-ticula, there is also a 

 small anterior pair, at the base of the first lateral pair. (8ee Plate II. fig. 4.) 



■■^ The slight difference ivhicli is to be observed in the diagi-am fig. 2, on the 

 inner side of the gland at the base of the fifth pair of appendages, was probably 

 caused by the fact that this point corresponds to a certain number of imperfect 

 sections. I think that for the rest, the diagram is sufficiently exact ; and if one 

 were to examine the coxal gland of Mi/gale ceeiacntana, I think it would be 

 found that its shape is very near to that indicated by the diagra)n. 



3 P.S.— March 20th, 18S5. After the reading of this paper, I was able to 

 consult Blanchai-d's " Organisation du regne animal." In the fig. 2, pi. xvi. 

 (Arachnides) of this work, one can recognize the coxal gland in the so-called 

 "glande stomacale." But the corresponding text, unfortunately, does not 

 exist.— P. P. 



