604 SUMMARY OF CURRENT RESEARCHES RELATING TO 



7natis Leydig aud D. j)hijlloides Csokor; the latter or pig parasite 

 is then compared with those found in man and in the dog, and its 

 three ecdyses — (1) between the egg and the six-footed larva; (2) 

 between the six- and eight-footed larva ; (3) between the latter and 

 the adult— are established. In the smallest tubercles in the skin 50-60 

 mites may be found, and in the larger 500-1000, The cast-off cuti- 

 cles are found towards the centre of the tubercle, the younger stages 

 towards the duct of the gland, and the adults towards the base and 

 periphery of the gland. Observation convinces the student that these 

 mites are air-breathers. From his specimens of pigs, Csokor is in- 

 clined to think that the transference of the parasite from pig to pig is 

 more easily effected than is the case with D. canis. 



S. Crustacea. 



larval Development of Phoxichilidium Plumulariae.* — R. v. 

 Lendenfeld gives some account of the early development of this new 

 species of Pantopoda. Among other points he notes the characters of 

 the pores on some of the appendages, which do not, as ordinarily, each 

 communicate with a group of glandular cells, but from each pore 

 there is a fine canal which leads into a well-developed primary duct, 

 at the centripetal end of which we find the gland. These glands are 

 large, saccular, or of an elongated pyriform shape ; each is solid, and 

 the protoplasm appears to be gradually converted into a secretion. 

 There are two of these glands, and, centripetally to them there is a 

 large stellate ganglion with a well-developed centripetally directed 

 nerve, as well as nerves for the glands. As maturity is reached the 

 hairs connected with these parts and the ganglia and nerves disappear, 

 but the glands remain, in rudiment, as a bilobed organ. The author 

 compares this form Math others already known, and points out the diffi- 

 culty of imagining how two species, both parasitic, could have arisen 

 from one and the same non-parasitic species, and how it is that the 

 larvas differ so much in their mode of development, while the mature 

 forms are almost completely unaltered. 



Relationships of the Malacostraca.j — In this important and 

 closely-argued paper J. E. V. Boas discusses the relationships one to 

 another of the great divisions of the Malacostraca, and directs atten- 

 tion to the characters of the appendages. The chief result of his 

 studies would appear to be that the Malacostraca are derived from the 

 Phyllopoda, of which Nehalia is their nearest ally. The group of 

 Malacostraca which stands nearest to the Phyllopoda is that of the 

 Euphausidse, and especially the genus Thysanopus. From a form 

 allied to this last the group of the Decapoda has been evolved ; but 

 they, as represented by their most primitive form (Penceidro), have 

 become so altered that it is not possible to follow those who have 

 placed the Euphausidtc and the Decapoda in one and the same order. 

 The Mysidacoio are also derived from a Thysmiopus-like form, and 

 their differences from the Schizopoda are so marked that it is hence- 



* Zeitscbr. f. Wise. Zool., xxxviii. (1883) pp. 323-9. 

 t Morph. Jahrb., viii. (1883) pp. 485-579 (4 pis.)- 



