198 SUMMARY OP CURRENT RESEARCHES RELATING TO 



close network of vessels communicating with those of all the viscera, 

 the most important being those which pass between it and the branchiae. 

 There are no vessels proper to the test. 



The elements of the blood are (1) cells with ramifying processes, 

 analogous to the lymph corpuscles of Vertebrata; (2) round or 

 mammillated refractive bodies of a deep brown colour, the result of 

 degeneration of the preceding. Both these kinds are also found in 

 the connective tissue everywhere, whither they seem to have migrated 

 from the blood ; (3) yellow granular cells, very scarce ; they resemble 

 the cells composing a special organ which is attached to the vas 

 deferens. 



The branchia is a network of thin-walled vessels ; its fundamental 

 elements are transverse vessels, which connect the afferent and efferent 

 vessels ; they are themselves connected by small longitudinal tubes ; 

 there are also two further series of transverse and one of longitudinal 

 vessels. The blood-vessels in general are excavated in the substance 

 of the connective tissue, where they form regular lacunae, whose 

 cavity is partially filled with connective tissue and lined with epithe- 

 lium. The heart is the only part of the vascular system which has 

 a complete muscular lining, although the superior and some of the 

 transverse branchial vessels possess isolated smooth muscular fibres. 

 The branchial vessels are distinguished by an unusually thin con- 

 nective tissue layer, covered externally by a pavement epithelium 

 which is ciliated in parts. 



In a subsequent paper * the histology of the species is described 

 in detail, for which the original text must be consulted. 



Mediterranean and Atlantic Bryozoa.f — M. Alphonse Milne- 

 Edwards gives a preliminary report of dredgings at great depths in 

 the Mediterranean and Atlantic Oceans from which it seems that the 

 full report will, among other things, add very largely to our know- 

 ledge of the Mediterranean Bryozoa. A list is given of 71 species. 

 The author says that Setosella vulnerata only seems to reproduce itself 

 at great depths, as he found ovicells on specimens from 1068 metres 

 while from less depths they are unknown. From having material 

 from more favourable ground he is able to give the form of the 

 ovicells of two species of Frondipora and BeticuUpora. As the 

 ovicells of so large a number of Cyclostomata are unknown this is 

 very important, both of these genera belonging to a form of growth 

 which is very sparely represented in the recent fauna, though 

 abundant in some geological formations. 



Arthropoda. 

 a. lusecta. 



Colour and Pattern of Insects.^ — Dr. H. A. Hagen considers that 

 colour and pattern are produced by physiological processes in the 



* Comptes Kendus, xcv. (1882) pp. 45-7. 



t " Rapport sur les Travaux de la Commission chargee par M. le Min. de 

 rinst. Publ. d'etudier la Fauue sous-mariue dans les grandes profondeurs de la 

 Me'dit. ct de I'Ocean Atlant., par M. Alphonse Milne-Edwards." Extr. des Arch, 

 des Missions Scientifique et Lit., ix. (1882). 



; Proc. Amer. Acad. Arts and 6ci., xvii. (1882) pp. 234-67. 



