752 SUMMARY OF CURRENT RESEARCHES RELATING TO 



iieck, the author proposes to call it Trachelifer ; as to its affinities, he is 

 unable to speak definitely. 



Life-history of Stenopus.* — Prof. W. K. Brooks reports on the 

 investigation made by Prof. F. H. Herrick and himself on the young of 

 this crustacean. The larvee are very much larger than ordinary pelagic 

 larvsB, and quite different from any known forms of Macrura. The chief 

 locomotor organs are the fifth thoracic legs, which are extremely slender, 

 as long as the entire body of the larvee, and ending in flattened elliptical 

 paddles, which are used as "sweeps" for rowing through the water. 

 Stenopus Mspidus has a cosmopolitan range, and in structure, habits, 

 colour, and external appearance is one of the most highly specialized 

 of Crustacea ; its antennae are long and slender, and the acuteuess of its 

 senses, together with its very remarkable alertness, the quickness with 

 which it perceives danger and the rapidity with which it escapes, have 

 undoubtedly aided it in holding its own whenever it has gained a footing 

 in a suitable locality. The upper surface of its body and limbs is 

 covered by a thorny armour of hooked spines, and as these all point 

 forwards, the attempt to swallow a Stenopus must be difficult and 

 painful. The length of its pelagic life is unquestionably an aid to its 

 wide dispel sal and to the discovery of new homes. 



The eggs, which are very small, are laid at night, and during seg- 

 mentation the yolk remains undivided. At the time of its escape the 

 larva is a Protozoea, and its later history is of great interest, as it unites 

 features of resemblance to Lucifer, Sergestes, Peneus, and to the prawns 

 in general. At the time of hatching it has sessile eyes, locomotor 

 antennge, an enormous mandible, a deeply forked pleon, a long rostrum, 

 and a complete series of appendages as far as the first pereiopods ; the 

 long hind-body has no appendage, and is only vaguely divided into 

 somites. Five or six hours after hatching it changes into a true Zoea, 

 much like that of an ordinary Macro uran. 



In the Mastigopus-stage the eyes are greatly elongated, and the third 

 maxillipeds are extremely long, while the huge oar-like fifth pereiopod 

 of the preceding stage is reduced to a bud, and the fourth is also reduced 

 and has only two joints. As in the Sergestidae, therefore, the last two 

 pairs of " walking legs " are shed after the Mysis-stage, to be again 

 reconstructed in tlie Mastigopus-s- age. After several months this last 

 larval stage gradually assumes the adult form, the principal changes 

 being the shortening of the eyes and the reaequisition of the fourth 

 and fifth pereiopods. 



Metamorphosis of British Euphausiidse-J— Messrs. G. Brook and 

 W. E. Hoyle give an abstract of their observations on the metamorphosis 

 of British EuphausiidaB ; the two most frequent forms are probably 

 Nydiphanes and Boreophausia. They give for the first time an account 

 of one almost complete series of moults for one species. In their meta- 

 morphosis the Euphausiida3 stand almost alone, none of the later larval 

 stages being identical with the Zoea and other larvae of Decapods. They 

 commence their life in the Nauplius condition, a type of larva frequent 

 in other groups. The larval formation of the antennae is retained until 

 the commencement of the Cyrtopia-stage, a feature which is not usual 

 among the Crustacea. The Calyptopis-stage, in which the compound 



* Circ. John Hopkins Univ., viii. (1889) pp. 29-30. 

 t Prnc. E. Poc. Edinb., xv. (18S7-8) pp. 414-20. 



