﻿T. Davidson — What is a Brachiopod? 199 



accomplished in about two hours, which was half the time it had 

 taken us to ascend. 



From the inhabitants we learnt that the mountain is regarded as 

 being holy, and that at certain seasons they make solitary pilgrim- 

 ages to its summit. We, however, had been the first to see the 

 eruption. 



Earthquakes, although so common on the mainland, are said not 

 to occur here ; and the only shocks that have been felt are those 

 which were produced at the time of the breaking out of the volcano. 

 This statement appeared to find some confirmation in the fact of a 

 strong earthquake having occurred in Yokohama and Yeddo at the 

 time of our making our inquiries, without being perceived by us. 

 Several other localities in Japan are reported as being free from 

 such annoyances ; but how far these statements may be relied on 

 needs investigation. Some of these districts are in the neighbour- 

 hood of recently active volcanos. If it is admitted that in the 

 immediate vicinity of certain active volcanos, earthquakes are un- 

 known, whilst in the surrounding districts they are strongly felt, 

 the idea would at once suggest itself that round these particular 

 volcanos, conditions exist which ward off the advance of any seismic 

 wave. Thus, for example, a lake of lava beneath the unaffected 

 area might accept a wave, but, for want of proper contact with the 

 the rocks above, would be unable to transmit its effect in their 

 direction. Owing to the state of the weather, and the short time we 

 remained upon the island, conditions were very unfavourable for 

 making accurate observations. 



Next morning we set sail for home, a distance which in coming- 

 had been traversed in only six hours; but in returning, through the 

 roughness of both wind and water, occupied two days. 



II. — What is a Bkachiopod ? 



By Thomas Davidson, F.R.S., F.G.S., V.P.P.S. 



PART II. 



(PLATES IX. AND X.) 



{Continued from the April Number, p. 155.) 



Muscles. — As the number and position of these organs differ 



materially in the two great divisions into which the Brachiopoda 



have been separated, and to some extent, also, in the different genera 



of which each division is composed, it may be desirable to treat this 



subject under two different heads.^ 



In the Clistenterata, of which the genus Terehratula may be taken 

 as an example, five or six pairs of muscles are stated by Hancock, 

 Gratiolet, and others to be connected with the opening and closing 

 of the valves, or with their attachment to, or movements upon the 

 peduncle. First of all, the adductors or occlusors consist of two 

 muscles, which, bifurcating near the centre of the shell cavity, pro- 



1 Unfortunately almost every anatomist who has written on the muscles of the 

 Brachiopoda has proposed diiferent names for each muscle ; hence much confusion 

 has arisen which can but be regretted. 



