1913-14.] Abnormal Echinoids in the Royal Scottish Museum. 247 
“ morphological units ” have remained intact, so that the left row of 
inter-ambulacrum 4 and the right row of inter-ambulacrum 5 were 
practically normal and were associated normally with the ambulacral areas 
in their respective “ arms.” On the other hand, the inter-ambulacral rows 
of arm V. bent away from their ambulacral area, the intervening space 
thus created being filled in by irregular small plates. But they ceased to 
exist at about the level of the truncated ambulacrum. Still a large area, 
measuring 12‘5 mm. in height from the termination of the truncated 
ambulacrum to the apical chain of plates, and 28 mm. from side to side, 
remained to be accounted for. This was filled in by a series of irregular and 
generally small plates arranged in lines roughly parallel to the circular 
periphery of the periproct. Considerable flattening has taken place in this 
growth area, which has thus been covered with the minimum of material. 
Of ambulacrum V. only about 1 cm. remained. The two pore rows, 
instead of approaching each other and meeting aborally to form a closed 
area, were parallel throughout, the open aboral end being filled in by small 
plates ; The individual rows of ambulacral plates in the disturbed area 
have suffered in different ways. The row to the left was perfect so far as it 
went as regards pore-pairs, but the right-hand row was shorter and for the 
latter half of its length was destitute of pores, except for three scattered and 
imperfect pore-pairs. 
Aristotle’s lantern was removed, and showed the normal skeletal 
arrangements. 
Soft Parts . — The dried remains of the soft parts were unsatisfactory. 
Three genital glands or portions of them were present, corresponding to the 
genital pores in areas 1, 2, and 3, but there was no trace of gland in 
connection with the abnormally situated pore supposed to be genital 5. 
The intestine was much broken, but it was noted that an upward loop in 
the middle of the abnormal area actually crossed the lower portion of the 
apical area, and that the intestine doubled on itself towards the anus in 
area 4, instead of, as usually occurs, in area 3. 
III. Total Variation from Five to Six-rayed Form. 
Echinus esculentus, Linn. 
Only one cake of this type has been observed in the collections — an 
example of Echinus esculentus, Linn., obtained in the Cromarty Firth by 
Mr F. G. Pearcey, at a depth between 8J and 16 \ fathoms. Examination 
of the shrivelled reproductive organs proves it to have been female. 
The specimen was preserved in a dry condition and, even clothed with 
