A HISTORY OF NOTTINGHAMSHIRE 



but the attempt is never for long successful. Nature continually interposes the necessity for 

 limitations, explanations, and exceptions. Names the most apt at the time of their choice may 

 easily become with the increase of knowledge inconvenient and misleading, so that we can only 

 continue to use them by shutting our eyes to their original significance. In the Diaptomidae 

 the first antennas in the female are divided into twenty-five articulations, and in the male the 

 right member of the pair is geniculate. The fifth pair of trunk-legs differ much in the two 

 sexes and are very unsymmetrical in the male. The female carries a single ovisac or external 

 egg-bag. The pleon in the male has five distinct segments, but in the female these are 

 reduced to two or three by coalescence. The latter sex in Diaptomus castor (Jurine), a species 

 which is found all over Europe, measures from a twelfth to a seventh of an inch in length, the 

 male not quite attaining the upper limit. But in determining the actual species with which 

 Mr. Edwin Smith was concerned, we are met with this difficulty. He says that it is ' easily 

 recognized by its inferior antennae, which are fully as long as the entire body.' It is obvious 

 that by the inferior antennae he really intends the first, and not the very much shorter second, 

 pair. But in Diaptomus castor the first antennae are ' unusually short, when reflexed reaching 

 but slightly beyond the anterior division of the body.' l There is, however, another allied 

 species, D. gracills (Sars), also found all over Europe, and described from England by Sir John 

 Lubbock (Lord Avebury) under the name of D. westwoodi, which has the first antennas even 

 longer than the body. This species, only a sixteenth of an inch long, is probably the one to 

 which Mr. Smith was really referring. 2 It is not a little important that in faunistic lists some 

 distinctive features of the creatures mentioned should be given, whereby verification of their 

 names may be made to some extent practicable. In regard to Cyclops quadricornis the two 

 authorities above quoted do not allude to any specific character. But the Linnean name 

 quadricornis has been applied to several forms which are now held to be distinct species. Thus, 

 according to Dr. G. S. Brady, F.R.S., the C. quadricornis of Lilljeborg is the same as the 

 Monoculus quadricornis rubens of Jurine, and should be called C. strenuus (Fischer), while the 

 M. q. albidus and the M. q. fuscus of Jurine he considers to be two varieties of the species 

 C. signatus (Koch). 3 On the other hand, Mr. J. D. Scourfield includes quadricornis in the 

 synonymy of three distinct British species, C. strenuus (Fischer), C. fuscus (Jurine), and C. 

 albidus (Jurine),* not to mention others which were regarded by Dr. Baird in 1850 as mere 

 varieties of one generalized type. 5 It is not only possible, but practically certain, that several of 

 these will eventually be found in this county. In C. strenuus and its near allies it may be 

 noticed that the anterior antennas are ly-jointed. They cannot therefore be confused with 

 Canthocampus minutus (O. F. Mtlller), in which the first antennas are only 8-jointed. The 

 hard structure to which Mr. Smith refers, as seen in connexion with the vulvular segment of 

 the female, was probably the spermatic tube. The genus, be it observed, is properly named 

 Canthocampus, not Canthocamptus. The species C. furcatus (Baird) has been transferred to 

 the genus Idya (Philippi), and being a marine species has no claim to our consideration here, 

 nor does Mr. Smith claim to have found it in local waters. Its range is wonderfully exten- 

 sive, since it occurs not only on the English coast, but also at New Zealand and in the 

 Chatham Islands. 6 



Professor Carr observes in his often quoted paper, ' Among the Entomostraca perhaps the 

 most interesting form is the fish-parasite, Argulus foliaceus (Linn). This beautiful and delicate 

 Crustacean I have found in numbers on bream taken from the Trent at Nottingham. 7 Here 

 we are fortunately left in no doubt about the species, since there is but one of the family 

 known in England. The only doubt is about its place in classification, whether it should be 

 ranged among the parasitic Copepoda, to which so many fish-devotees belong, or should be 

 allotted to a special division of the Branchiopoda called Branchiura or gill-tails. As will be 

 seen from Baird's bibliographical history of the genus, 8 these animals have courted the attention 

 of more than one distinguished naturalist. The celebrated Cuvier kept some alive under 

 special observation. He noted that the eggs were deposited in two compact straight lines on 



1 G. O. Sars, Crustacea of Norway, iv, 85 (1903) ; and Giesbrecht and Schmeil, Das Tierreic6 t 

 Copepoda, pt. i, 88 (1898). 



3 Sars, op. cit. p. 92, pi. 63 ; Giesbrecht and Schmeil, op. cit. p. 72. 

 8 Nat. Hist. Trans. Northumb. etc. vol. xi, pt. i, 71, 73 (1891). 

 * Journal Quekett Microscopical Club, 533, 535 (1903). 



5 British Entomostraca, Ray Soc. pp. 198, 203 (1850). 



6 Sars, Zool. Jahrb. vol. xxl. pt. iv. 380 (1905). 



7 Trans. Nott. Nat. Soc. for 1902-3, p. 2. 8 Brit. Entomostraca, p. 242. 



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