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forward anil somewhat downwanl and serve as base of altachnicnt for powerfnl 

 tendons in the muscnlatuie whicli moves the tail. The posterior vertebræ have 

 very indistinct traces of these processes. Lower arches representing probably the 

 true transverse processes are also present on the vertebræ from the 7th; on the 

 7th anil 8th the lower arch is quite short, almost ring-shaped, surrounding the 

 large blood vessels; on the 9th vertebra the arch begins to be greatly prolonged 

 downwards, forming an inferior spine; for this reason I count this as the first 

 caudal vertebra. Between the spinous process on the second last caudal vertebra 

 and the urostyle on the last we find in A. strigata 2 independent skeletal parts, 

 one between the very broad, lower spinous process on the second last vertebra 

 and the broad hypural bone on the last; in A. scutata I find one piece at each of 

 the corresponding places. 



Ribs are quite wanting. 



In the vertebral column the whole anterior part formed by the 6 elongated 

 vertebræ is stiff, immovable; the connection with the cuirass would alone prevent 

 movement; with this agrees, that the transverse processes are suturally connected 

 with one another, whilst the corpora of the vertebræ are simply juxtaposed just 

 as in movable vertebræ. 



Interspinous bones. 1. Of the dorsal fins (Tab. II, fig. 1). To each of the 

 first 4 vertebræ corresponds an interspinous bone, which is placed close to the 

 anterior face of the spinous process of the vertebra. There are no interspinous 

 bones for the 5th and 6th vertebræ, but interspinous bones again appear in 

 front of the spinous processes of the vertebræ 7 — 10. Between the vertebræ 

 10 and 11 there are 2, also between 11 and 12, 12 and 13; between 13 and 14 

 there is 1, the hindmost''. 



Some notes may be given on the 4 members of the first group. The first 

 (PI. II, fig. 1, 1) forms a vertical plate in front of the spinous process and with its 

 somewhat widened upper border reaches to the inner surface of the cuirass in 

 A. scutata: in the other two species this upper border is wider still and shows itself 

 externally in the middle line of the dorsum as the previously mentioned small 

 unpaired dorsal plate; behind the point of the spinous process the interspinous 



* This is tlie condition I find Ijotli in A. scutata and in the specimen examined of A. striyata, 

 whicli was provided with 3 spines behind the dorsal spine; of these however only the first two were 

 noticeable from the outside. Two noticeable spines are most probably the normal for the species 

 strigata; but 1 believe I could detect a short 3rd on several specimens, hidden in the soft parts, closelj' 

 pressed to the peculiar, rayless interspinous bone (* in PI. II. fig. 1), the cartilage of which is fused to 

 the one which bears the first ray of the 2nd dorsal fin; 1 imagine therefore that most specimens will 

 be as described, thus agreeing witli scutata which has normally 3 apparent spines. More spines can 

 sometimes be found however in strigata; 1 have before me a specimen from Amboina with 4 apparent 

 spines, of which the two following on the dorsal spine are thin and fine, the next two of the usual 

 form, with lancet-like, compressed point. In A. punctulata there are two apparent spines, as is usual 

 iu strigata; if it should prove — which I have not been able to determine — that there is another 

 hidden spine, the above account will hold good generally for the genus Ampliisile. 



