LIVING BRACIIIOPODA. 371 



EXTERNAL GLANDS. 



A curious paired organ of which I published a short account some years ago ('72) has, 

 with this exception, never been observed before. These organs are found clustered 

 around the exterior nipple-like openings of the nephridia in T. septentrionalis. Plate 60 is 

 devoted to illustrations of these bodies. They form conspicuous, white, lobulated masses 

 arising from the space between the external orifices of the nephridia. The lobules, to the 

 number of ten or twelve, vary in shape from one another, and are by no means alike on 

 each side ; in this respect forming a marked exception to the strictly bilateral and syrnmet- 

 rical repetition of parts in the Brachiopoda. In one instance a peculiar lobulated structure 

 ensheathed the nephridial tube, apparently within the coelomic wall (60: 8). It seemed to 

 be of the same nature as the external glands. A distinct wall surrounds each lobule, 

 though this wall varies in thickness, being somewhat thicker at the extremities. The 

 lobules stand quite free from each other and have a narrow base of attachment. They all 

 seemed to be clothed with a ciliated epithelium. Under pressure, irregular granules were 

 forced out and these vibrated in such a manner that I fii'st mistook them for spermatic 

 particles. At 60: 12, is represented the appearance of these lobulated masses as seen 

 from below. They stand quite free and prominent from the coelomic wall. Between 

 these masses is seen a distinct prominence ; viewed from in front, this prominence is 

 bordered by an encircling line (60: G) . In 60: l, its position in relation to the mouth 

 and other parts is shown ; in this figure, also, a clear idea may be had of the position 

 of the external glands in relation to other parts of the structure. In 60: 13, a rough 

 outline is given representing a longitudinal section of T. septentrlonalis for the purpose 

 of indicating the exact position of the external glands in relation to other parts of the 

 anatomy. The spiculae which abound in the pallium, brachia, and cirri of this animal, 

 are also found in the external layer of these glands (60: 5, 7, lo) . 



Precisely what may be the function of these external glands I do not know. 

 Mucous secretions occur abundantly about the external openings of the nephridia and the 

 mouth, and it may be that these are simply mucous glands. Whether they may be com- 

 pared to the dermal glands of the chaetopod worms is a question, though it is stated that 

 the dermal glands in worms form an investment for the ova; but the ova of Terebratulina 

 are not invested with mucus. With the idea that they are glandular, I have given to 

 them the name of external glands. I have not observed them in other Testicardine 

 forms, though they will doubtless be found. From their intimate association with the 

 external ducts of the nephridia, it seems reasonable to believe that in some way they are 

 connected functionally with the genitalia. 



