ZOOLO&Y AND BOTANY, MICROSCOPY, ETC. 35 



exposed bodies of a small crustacean, Hippa talpoidea, and that the 

 water in passing over the bodies, made the trifid marks which had 

 been taken for impressions of birds' feet. This little creature took 

 shelter in the sand near low-water mark, and entered head foremost 

 in a perpendicular direction downwards, resting just beneath the 

 surface. The returning wave took some of the surface sand with it, 

 and thus the lower portions of the bodies, uppermost in the sand, were 

 exposed. Often the creatures would be washed out, when, recovering 

 themselves, they rapidly advanced in the direction contrary to the 

 retreat of the wave, and entered the wet sand again as before, their 

 sides being parallel with the shore. The body terminated in a 

 caruncular point which, with the position of the two hind-legs, made 

 a tridentate obstruction to the sand brought down by the retreating 

 wave, and the water passing around the points, made the three toe- 

 like grooves which resembled a bird's foot from 1^ to 2 in. long. 

 The creatures in their scrambles for protection beneath the sand, 

 managed to keep at fair distances from each other, and hence there 

 was considerable regularity in the tracks as if they had really been 

 produced by birds. 



He added that he presented the observation as a mere trifle, but 

 he could not help remarking that if by any means these trifid im- 

 pressions should get filled with mud, and the deposit become solid 

 rock, it would be very natural for observers, ignorant of their origin, 

 to mistake marks like these for the tracks of birds. 



B. INVERTEBRATA. 



Anastomoses of the Striated Muscular Fibres of Invertebrates.* 

 — M. Jousset de Bellesme has endeavoured to determine the function 

 of the anastomoses which are found in the primitive bundles of the 

 striated muscles of Invertebrates, the same existing in Vertebrates 

 only in certain special organs, such as the heart. 



As the result of his observations on the larvae of Insects and on 

 Crustacea (more particularly Amphipoda and Isopoda) it appears first, 

 that there is no necessary relation between the striated condition and 

 the accomplishment of voluntary movements, as striated fibres are 

 found in the digestive tube and its glandular appendages, and 

 secondly, that there is a constant relation between the fact of this 

 anastomosing and the mode of contraction of the organs which have 

 this arrangement. 



Prom the transparency of the Crustacea studied it was seen that 

 the contraction of the fibres of the gastric ceeca exactly resembled that 

 of the Vertebrate heart. The products of secretion accumulate in the 

 centre of these tubes and it is therefore essential that their walls should 

 contract simultaneously (and not one part after another) in order to 

 expel the secretion. It is this simultaneousness in the contraction that 

 it is the function of the anastomoses to secure, and it is not without 

 interest to see that the same effect is produced in the muscles of both 

 Vertebrates and Invertebrates by the same organic arrangement. 



* Comptcs Rendus, xcv. (1882) pp. 1003-4. 



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