1907.] NATUUAL SCIEN'CES OF PHILADELPHIA. 121 



(fig. 22), with the smaller end tliix'ctcd downwanls, and continued as 

 a very slender duct. The ducts from each group unite to form a 

 bundle (text fig. III. A, and fig. 20. c.gl.d.). Each of these passes 

 downward and slightly forward, penetrating in their course the lateral 

 portions of the brain. On meeting the ventral hypodermis the ducts 

 of each side diverge, most of them turning inwards (mesiad), and, 

 penetrating the hypodermis, open on the ventral surface; the mouths 

 of the ducts forming a line transverse to the long axis of the animal, 

 just posterior to the anterior end of the head. Just before its termina- 

 tion, each duct displays a bulbous enlargement, forming a small 

 reservoir. The cephalic gland cells much resemble those of the salivary 

 glands in their cytological characters and staining reaction. Like 

 the latter, the protoplasm of the cephalic glands absorbs many chro- 

 matin stains with avidity, being stained with especial intensity in 

 Delafield's hiematoxylin and in carmine, while iniaffected by muci- 

 carmine. "With iron-hajmatoxylin it is usually colored only a dark 

 gray. In certain cases, as in the one represented in fig. 22, intracellular 

 spaces, which previously had evidently been occupied by secretion, 

 were present in the cytoplasm. 



Glands corresponding to the cephalic glands have been described 

 only in the account given by Schimkewitsch (1895) of D. metameroides, 

 although this author suggests their occurrence in D. keniatus, inferring 

 this from Harmer's (1889a) description and figures of the brain. 



The function of the cephalic glands is problematical. Their situa- 

 tion, just anterior to the preoral field of cilia which serves to sweep 

 food particles into the mouth, suggests that they may perform a 

 digestive function. Whether this is the case or not, their great size 

 indicates that their function must be an important one in the economy 

 of the animal. 



5. Excretory Organs. 



Nephridia. — Dinophilus conklini possesses five pairs of nephridia, 

 metamerically arranged and corresponding to the five posterior trunk 

 segments. The first of the five pairs differs from the others in that its 

 structure is relatively much more complex; for that reason it will be 

 more convenient to defer the consideration of this pair to the last, and 

 to describe first the simpler structure of the posterior four pairs. 

 These are very tenuous and ill defined in structure, in fact so much so 

 that for a long time I failed to recognize them as definite organs, and 

 mistook them for mere strands of mesenchymatous or connective tissue . 

 In general structure, however, they were found to correspond closely 



