730 SUMMARY OF CURRENT RESEARCHES RELATING TO 



fundamental unity of structure of the heads of all insects, but how far 

 and in what directions it is varied, and what is its relation to other 

 parts of the body are questions needing further research. 



Aquatic Larvae of Lepidoptera.* — M, C. Maurice points out 

 that, strange as it may seem, aquatic caterpillars are to be found in 

 nearly every group of the Lepidoptera. He describes the presence 

 in Paraponyx stratiotata of a system of tracheal gills, in which the 

 delicate membranes provide for the animal's respiration an endos- 

 mosis of oxygen and an exosmosis of carbonic acid. Stigmata are, 

 moreover, to be found in the thoracic regions of these forms, but 

 they are not functionally active during the larval stage as they are 

 closed by a delicate membrane, and they do not become useful till 

 the marsh in which these larvae live becomes dried up. The author 

 is unable to decide the question whether Parapow/x is a degraded 

 form, or whether it does not indicate a connection between the Lepi- 

 doptera and the lower orders of insects. 



Attention is finally drawn to the proofs lately given that aquatic 

 larvse are to be found in the families of the Bombyces and Sphingidfe, 

 but it is pointed out that in neither of these cases is there as yet any 

 evidence as to the presence of tracheal gills. 



Relation of Devonian Insects to Later and Existing Types. — 

 In 1862 the fragments of six insects were discovered in the Devonian 

 strata of New Brunswick and were considered to be the oldest known 

 fossil insects. They form the subject of an elaborate memoir,t by 

 Mr. S. H. Scudder (having been preceded by other communications), 

 of which the most important conclusions were given ante, p. 236. 



Dr. H. A. Hageu,| however, arrives at conclusions radically 

 different from those of Mr. Scudder, and in particular he states that 



(1) the fragments belong to five species of Odonata and Neuroptera ; 



(2) none of them have any relation to the Ephemoridte ; (3) none ai-e 

 of a synthetic type ; (A) the previous stages of all were probably 

 aquatic ; (5) no related species is known from the North American 

 Carboniferous strata — probably all insects known from them are 

 terrestrial ; (6) the four families proposed by Mr. Scudder are based 

 upon extremely vague characters, not properly family characters. 



7- Arachnida. 



Pycnogonida of the "Blake" Expedition. §— Mr. E B. Wilson 

 reports upon this collection of ten species dredged in 1880 off the 

 eastern coast of the United States at a depth of 73-1242 fathoms by 

 Pi of. A. Agassiz. The most striking feature is the remarkable size 

 of most of the forms, which may fairly be called colossal in com- 

 parison with shallow- water or littoi-al species. Of the three species 

 of Colosse7ideis (two apparently new), the smallest has a span of 

 14 cm. between the tips of its outstretched legs, while the largest has 



* Bull. Sci. Dep. Nord, iv. (1881) pp. 11.5-20. 



t Anniversary Mem. Bost. Soc. Nat. Hist., 1880, 41 pp. (1 p].). 



X Bull. Mus. Conip. Zool., viii. (1881) pp. 275-84. 



§ ll)id., pp. 239-.')(; (.5 pis.). 



