ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 563 



belonging to the order of the Siphonostomata, and especially to the 

 Pelticephalidae, of the genera Nogagiis, Lepimacrus (nov. gen.), 

 Pandarus, and Cecrops ; all of these have been described and figured 

 from living examples ; they all live on fishes with an extremely thick 

 skin, the scales of which are so closely arranged as to render 

 penetration extremely difficult, and they all have a very special form 

 of buccal apparatus, consisting of a rigid tube which is narrowed at 

 its extremity, and which is deeply plunged into the flesh of the host 

 BO as to di-aw from it the fluids necessary for food. The fishes are 

 all members of the group of the Squalidas. 



After a full description of Nogagus spinacii [N. achantias), we have 

 an account of an attached embryo ; the latter was 3 mm. long by 1 

 wide ; it was provided anteriorly with an umbilical process which 

 served as an organ of attachment, but was so flexible as to be able to 

 be turned in various directions ; on either side of this were a pair of 

 long flattened antennae formed of two joints, at the end of which were 

 several divergent hairs. The eyes were relatively large and not 

 widely separated from one another. The body was tubular in form 

 and consisted of five rings, the first of which served as the point of 

 attachment. These embryos were very active and lively, and on several 

 occasions were seen to be living, even when the Crustacea to which 

 they were attached were far gone in the way of decomposition. 



The new genus Lepimacrus is founded on a single female specimen 

 found on Lanina cornubica ; the species is called L. jourdaniL 



Several species of Pandarus and one of Cecrops are next described ; 

 and this is followed by some notes on their " physiology " and " bio- 

 logy." It is pointed out that the mucilaginous tegumeutary secretions 

 of the piscine hosts render the skin more supple and more easily 

 penetrable by the organs which attempt to perforate them. When 

 deprived of this advantage and incompletely fixed to a thick and 

 coriaceous envelope they easily fall off when the fish is captured and 

 withdrawn from the water, and are then difficult to find.* The jjara- 

 sites of the Squalidae may be seen to select the thinnest parts of the 

 skin, such as the axillse or the eyes. Scyllium canicula, catulus, and 

 annulatus have never been found to be infested with parasites, and it is 

 a significant fact that their skin is very thick. 



Hesse is of opinion that Nogagus should be placed with the Pan- 

 darina^ rather than the Caliginaj : and has some remarks on the term 

 Siphonostomata, which has been rightly applied to those Crustacea, 

 which, like the Pandarina, have a special syphonate buccal apparatus, 

 by means of wliich they are able, after having pierced the skin of tho 

 fishes upon which they live, to penetrate their flesh and draw thence 

 their nutriment ; this apparatus is not, however, found in Argulus, or 

 Caligus, which arc ordinarily associated with them. (It may bo 

 observed that one of the best authorities on the Copepoda — Professor 

 Claus — makes a special division — that of the Branchiura — for Argulus.) 

 Tho forms just mentioned bite rather than prick. For tho Argulina 



• It may be pr)itite(l out, in thia connection, that the number of paraBltic 

 Copcpodu collected by tho ' Challeugcr ' waa very eumll. 



