REPORT ON THE PYCNOGONIDA. 105 
Different as the forms of these spines may be, their minute structure is always the 
same, and, I think, quite identical with that of any other spine. The cuticle is perforated 
at the place where the spine is inserted, and a thin and flexible part of this cuticle keeps 
the spine in its place; a socket is thus formed in which the spine easily moves. The 
spine itself is, near its imsertion, cylindrical and hollow, and its cavity is entirely or 
partly filled with a protoplasmic substance, which is in continuity with the epithelium 
of the integument. Towards the extremity the spine is flattened, chitinous, and no 
longer hollow; the exterior margin of this flattened part is serrated (Nymphon), or 
provided with extremely small teeth (Colossendeis). Originally I considered these spines 
as being of a sensory nature ; but afterwards, as I was convinced of their chitinous composi- 
tion, I changed my opinion. However, as it is not difficult to trace a nerve, at least in 
some of the more transparent species, penetrating these spines, they may still be considered 
as, to a certain extent, organs of feeling. On the other hand there are, perhaps, far more 
important functions to be fulfilled by the ovigerous legs with the aid of these denticulate 
spines, viz., those of seizing the food, and, last, not least, of holding the animal of the 
other sex during the act of copulation. In most species where denticulate spines occur 
the four last joimts of the ovigerous legs often lie rolled up spirally, with the rows of 
denticulate spines turned inwards. These joints if wound round one of the legs or any 
other part of the body of the animal with which it copulates, would necessarily secure a 
very strong adhesion in consequence of the rows of spines. 
In close relation with the integument are the glands, which occur in different 
appendages of the body. 
1. The glands of the palpi. These I observed in Discoarachne brevipes, where they 
occur in the third joint of the palpi, and probably their secretion is poured out through 
a sieve-like perforated spot at the end of the second joint (Pl. VII. fig. 10). In the 
palpus of Ascorhynchus such a gland is also present. It is situated in the fifth joint, and 
has the form of a long sack, whose wall is lined by small and very numerous glandular 
cells. It is attached to the wall of the jot of the palp by means of numerous threads 
of connective tissue, and it opens towards its distal extremity by means of a rounded 
pore. In Ascorhynchus orthorhynchus this pore is placed at the tip of a small conical 
excrescence ; but in Ascorhynchus glaber I did not observe this knob. Probably the 
same glands occur also in other genera—e.g., in Colossendeis—but I could not ascertain 
their presence.’ 
2. The glands of the ovigerous legs. These I observed in Nymphon, but their minute 
structure can only be studied in fresh specimens. They open into a small pore, not far 
from the beginning of the fourth joint of the leg. Hach gland seems to consist of the 
1 The glands of the palpi are mentioned in Dohrn’s paper of 1879. He says of the nerve of the palpus: “Er um- 
fasst auf seinem Laufe ein sonderbares, bisher unbekannt gibliebenes Excretionsorgan” (loc. cit., p. 31). 
(ZOOL. CHALL. EXP,—PART x.—1881.) K 14 
