Alcock, Bouvier giving support to this opinion by the sutural or other divisional lines in _Potamobius_, _Nephrops_, _Thalassina_, and various fossil genera. Not all questions of classification internal to this division are yet finally settled. Between the Brachyura and Macrura some authors uphold an order Anomura, though in a much restricted sense, the labours of Huxley, Boas, Alcock and conjointly Alphonse Milne-Edwards and Bouvier, having resulted in restoring the Dromiidea and Raninidae to the Brachyura, among which de Haan long ago placed them. The French authors argue that from the macruran lobsters (_Nephropsidae_) anciently diverged two lines: one leading through the Dromiidea to the genuine Brachyura; or crabs, the other independently to the Anomura proper, which may conveniently be named and classed as _Macrura anomala_. Spence Bate maintained that the Schizopoda ought not to form a separate order, but to be ranged as a macruran tribe, "more nearly allied to the degraded forms of the Penaeidea than to those of any other group" (_"Challenger" Reports_, "Macrura," p. 472, 1888). According to Sars, the Sympoda (or Cumaceans), in spite of their sessile eyes, have closer affinities with the stalk-eyed orders. H. J. Hansen and others form a distinct order Tanaidea for the decidedly anomalous group called by Sars _Isopoda chelifera_. 1. BRACHYURA.--For the present, as of old, the true Brachyura are divided into four tribes: _Cyclometopa_, with arched front as in the common eatable crab; _Catometopa_, with front bent down as in the land-crabs and the little oyster-crab; _Oxyrhyncha_, with sharpened beak-like front as in the various spider-crabs; _Oxystomata_, including the Raninidae, and named not from the character of the front but from that of the buccal frame which is usually narrowed forwards. In these tribes the bold and active habits, the striking colours, or the fantastic diversities of structure, have so long attracted remark that recent investigations, while adding a multitude of new species and supplying the specialist with an infinity of new details, have not materially altered the scientific standpoint. New light, however, has been thrown upon the "intellectual" capacity of Crustacea by the proof that the spider-crabs deliberately use changes of raiment to harmonize with their surroundings, donning and doffing various natural objects as we do our manufactured clothes. Others have the power of producing sounds, one use to which they put this faculty being apparently to signal from their burrow in the sand that they are "not at home" to an inopportune visitor. Deep-sea exploration has shown that some species have an immensely extended range, and still more, that species of the same genus, and genera of the same family, though separated by great intervals of space, may be closely allied in character. A curious effect of parasitism, well illustrated in crabs, though not confined