96 ANNALS OF SCOTTISH NATURAL HISTORY 



a head and vertebral column, but no trace of jaws or limbs ; 

 and, strange to say, all the specimens are seen only from the 

 ventral aspect, as is shown by the relation of the neural arches 

 to the vertebral centra. The head is in most cases much 

 eroded, but its surface is fairly well seen in the specimen 

 represented in Plate III. Fig. 5. It is divided by a notch on 

 each into two parts : anterior (A/.) and posterior (/>..) The 

 anterior part shows a groove the edges of which are elevated, 

 while the surface on each side shows two depressions like 

 fenestrae (b. and c.\ though perhaps they are not completely 

 perforated, and also a groove partially dividing off, posteriorly 

 and externally, a small lobe (a.} In front there is a ring- 

 like opening (;/.) flattened by pressure, surrounded by small 

 pointed cirri, four ventrally (v.c.}, at least five dorsally (d.c.}, 

 and two long lateral ones (I.e.} which seem to arise inside the 

 margin of the ring instead of from its rim like the others. 



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The posterior part of the cranium is flattened, but the median 

 groove is still observable. Connected with the posterior or 

 occipital aspect of the skull are two small narrow plates (.r.) 

 which lie closely alongside the first half dozen vertebrae. 



The bodies of the vertebrae are hollow or ring-like, and 

 those immediately in front are separated from each other by 

 perceptible intervals (restoration, Fig. 8) ; their surfaces are 

 marked with a few little longitudinal grooves, of which one 

 is median. They are provided with neural arches, which are 

 at first short and quadrate, but towards the caudal extremity 

 lengthen out into slender neural spines, which form the 



o 



dorsal expansion of a caudal fin, while shorter haemal ones 

 are also developed on the ventral aspect. In one specimen 

 which has the tail exceptionally well preserved, these neural 

 rods or spines are seen to be twice bifurcated towards their 

 extremities (Fig. 6). 



As I have already stated, none of the numerous specimens 

 which have occurred show the smallest trace of jaws or of limbs. 



The anterior moiety of the skull (t.p.} I interpret as 

 equivalent to the trabeculo- palatal part of the cranium of 

 the Lamprey, the posterior to the parachordal part and 

 auditory capsules. The cirrated ring (;/.) receives its most 

 obvious interpretation as the median nasal opening of a 

 Marsipobranch, while the small lobe (a.} strangely suggests in 



