152 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 



upon a few other forms. The first extensive comparative work was that 

 of Grohben ('80), who studied these organs in a number of Entomostraca 

 and Malacostraca, and sought to prove them homologous in the two 

 groups. 



The earliest evidence of the excretory function of these organs was 

 afforded by Will und Gorup-Besanez ('48), who made the following 

 statement (column 828) : "... in der That haben wir im sogenannten 

 griinen Organ des Flusskrebses (Astacus fliwiatilis) und im Bojanus'- 

 schen Organ des Teichmuschel ( Anodonta) einen Stoff aufgefunden, der 

 Reaktionserscheinungen zeigte, die mit der grossten Wahrscheinlichkeit 

 auf Guanin hinweisen, doch gebrach es uns bisher an dem nothigen 

 Material, urn entscheidende Versuche damit anzustellen." Similar chem- 

 ical experiments were carried on by several later investigators, but the 

 most conclusive evidence of the excretory activity of these organs rests 

 upon extensive experiments in intra vitam injection and feeding which 

 were inaugurated by Kowalevsky ('89), and extended in subsequent 

 papers by him and by other authors, especially by Cuenot ('94). 



By far the most comprehensive work on excretion in Crustacea is that 

 of Marchal ('92). Until the publication of this work, the major part of 

 the literature, especially as regards histology, was on Astacus, with addi- 

 tions on some of the Carididse (Grohben '80, Kowalevsky '89, and 

 Weldon '89 and '91). Marchal in his memoir gives the results of a 

 careful reseai'ch on the morphology, histology, and physiology of a long 

 series of species representing all the typical genera of the Decapoda. 

 The work was carried on by the methods of modern technique, including 

 the intra vitam method of Kowalevsky ('89). 



This is the only paper that deals with the antennal gland in Homarus. 

 The species studied by Marchal (H. vulgaris), however, was not the 

 same as that of the present paper. In H. vulgaris, according to Mar- 

 chal (pp. 156-163), the gland presents an entirely different appearance 

 from that seen in Astacus, although the main divisions into gland proper, 

 vesicle, and duct are found in both. In H. vulgaris the gland as seen 

 from above is triangular in shape, the antero-posterior axis being the 

 longest. The posterior tip is curved mediad, and the periphery is more or 

 less notched. The dorsal face is slightly concave, the ventral markedly 

 convex. 



The structure is much less complex than in Astacus, and there are 

 two distinct regions besides the duct, — the saccule and the labyrinth. 

 The former is thin and flattened out over the dorsal face of the gland, 

 covering it except for a narrow projecting margin. The saccule has a 



