624 DR. H. CHAELTON BASTIAN ON THE ANATOMY AND PHYSIOLOGY 



In these lateral vessels, even when they were fairly exposed to view by being squeezed 

 out from the cavity of the body of adult specimens of Tylenclms tritici, no granules 

 or cilia could be detected ; they appeared to me to contain a colourless fluid, though 

 Davaine* described it as "legerement rougeatre," and also spoke of the lateral vessel 

 itself as " susceptible de contractions et d'expansions alternatives et lentes." 



The Echinoderms have long been remarkable for the number of pores of different 

 kinds, opening either through their calcareous external skeleton, or through their cori- 

 aceous integument as existing in the Holothuriadce ; and from what I have made kno^vn 

 in the earlier portion of this memoir concerning the prevalence, and in some species 

 amazing number of integumental channels met with in the Nematoids, it becomes an 

 interesting question to ascertain whetlier any resemblance, either as regards distribution 

 or function, can be traced between these structures in the two gi'oups of animals. 



In the Echinoderms these pores are of three kinds ; first and by far the most numerous 

 are the so-called "ambulacral pores," mostly arranged in double series along the five 

 pairs of ambulacral avenues radiating from the mouth and destined to give exit to the 

 tubular feet in connexion with the ambulacral vessels. In some Echinoderms these are 

 the only kind of pores existing, but in the Asteriadce there are on the antambulacral 

 surface other pores through which protrude small ciliated tubes imagined to have a 

 respiratory function. In the Starfishes these are generally aggi-egated into groups f. 

 Pores probably having a similar function are met with also in some Crinoids ; "but it is 

 in the Cystideans that this system of antambulacral pores attains its greatest develop- 

 ment" J. StiU other pores, larger and definite in number, have been met with in the 

 Echinoderms. Professor Forbes, speaking of Crihella oculata, one of the Asteriadse, said : 

 — " It received its name of oculata, either on account of the moniliform pores, or the five 

 dark spots which occasionally mark the origin of the rays. The pores on the surface 

 are not characteristic of this genus only, as Professor Agassiz seems to think. They 

 may be seen in many other Starfishes, and in the young of almost all the species. In 

 the living animal a brownish peritoneal membrane pouts out at each pore. Are they 

 not subservient to respiration" §^ He says, moreover (p. 152), that five similar pores 

 are to be met with in most of the Sea-Urchins. Here we have, then, amongst the Echi- 

 noderms i)ores subservient to two distinct uses, the one locomotoiy in relation with the 

 highly developed ambulacral system of vessels, and the other respiratory, whilst of these 

 latter there are two varieties, those of the one set being small, numerous and indefinite in 

 number, whilst those of the other are definite and much larger in size. 



In the Nematoids two varieties of integumental pores are met with : one kind con- 

 sisting of the two large, lateral, cervical pores, together with the two similar latero- 

 ventral, caudal pores, which perhaps may be analogous to those last mentioned as 



* Eecherches sur I'Anguillule du ble nielle, 1857, p. 28. 



t SiiARPET, art. Cilia, vol. i. p. 615, and art. Ectinodermata, vol. ii. p. 40. Cycl. of Anat. and Phys. 



J HuxiEY, Med. Times, 1856, ii. p. 657. 



§ Hist, of Brit. Starfishes, 1841, p. 101. 



