128 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



be sometimes united into groups of five or six, and. in the intervals small hairs ' occur 

 upon the surface of the cuticular lining*. 



Cano (32) devotes considerable attention to this subject, in a paper published in 

 1891, describing the distribution and structure of the cement glands in a large 

 number of decapods. Bumpus attributes the "varnish-like layer" which surrounds 

 the ovum of the lobster after oviposition to a secretion which is supposed to come 

 from the columnar cells lining the oviducts (30). 



In 1893 I gave a short and incomplete account of the cement glands of the 

 lobster (96). See also 57, note p. 79. 



TEGUMENTAL GLANDS IN OTHER PARTS OF THE BODY. 



I am not able to map the entire distribution of the tegumental glands, but have 

 found them in many parts. The labruin and metastoma are packed almost full (fig. 

 208, plate 49). In the latter the ducts open for the most part upon the side next the 

 mandible. We find them also in the basal stalk (protopodite) and respiratory plates 

 of the maxillae and maxillipeds, where they are already developed in the larval stages 

 (plate 29, figs. 59, 62), and in the flagella of the antennae. 2 The skin of the carapace 

 and abdomen abound in these organs, and they are clustered in large numbers about 

 the anterior lower margins of the former, just below the cervical groove, where the 

 surface of the shell is raised into prominences like a grater. The ducts of many of 

 these glands open into the respiratory cavity. I have also found a few of the organs 

 in the walls of the seminal receptacle. 



In sections through the dorsal posterior surface of the carapace of a lobster nearly 

 ready to molt I find glands in precisely the same condition as shown in fig. 211, plate 

 49, where there is an inner deeply staining granular zone. Figure 208, plate 49, rep- 

 resents an organ from the metastoma, after maceration for three days in Bela Haller 

 mixture and staining in methylen blue. The duct, running in the nerve bundle, 

 shows very clearly and can be readily traced to the surface of the gland. By focusing 

 with care I was able to follow the tubular duct into the central lumen or space, so 

 characteristic of these organs. The relative number and distribution of glands in 

 any part can be determined from macerated portions of the shell, as in fig. 170, which 

 represents the inner surface of the first maxilla. 



By maceration and pressure the structure of the gland can be made out in most 

 of its details. In fig. 203, plate 49, the eccentric "ganglion "cell (s. c.) is seen to give off 

 two branches, one of which joins the rosette (R), while the other passes into the nerve 

 bundle, not shown in this drawing. A single gland cell is still joined to a process 

 of the rosette by its attenuated central end. By rolling this specimen under the 

 cover slip I was able to confirm the relations here pointed out. In fig. 214, drawn 

 from a similar preparation, fewer glandiilar cells are detached, and but one process of 

 the "ganglion" cell is shown. In many instances I have noticed that the inner ends 

 of the gland cells have a very refractive, tubular appearance where they join the 

 central rosette (figs. 209, 213, etc., plate 49), as if they had been snapped off at this 

 point of delicate union. Figs. 206, 207 show a single gland cell drawn from opposite 

 sides, from a cement gland of a female with nearly ripe ovaries. Besides the promi- 



I I think it probable that the ducts of the glands really open upon these "hairs," as they do in 

 the labrum. (See p. 133.) 



-I have seen them in the outer fiagelluni only of the first antenna. 



