64 
Fig. 2. 
Hybrid of Echinus esculentus and Parechinus miliaris. Nat. size. 
an Echinus whicli at once attracted ray attention. It seemed to 
be Ech. esculentus , but looked, however, rather different from the 
usual appearance of this species. On examining the specimen more 
closely later on I found my first impression confirmed — it was 
an Echinus esculentus , but one differing in some important charac- 
ters from the usual form. I may give here a description of the 
specimen (Fig. 2). 
The diameter is 53 mm, the height 28 mm. The nurnber of 
ambulacral plates is 42, that of the interambulacral plates 21 in 
each series. The shape of the test is unusually low, as in the 
variety fuscus. In the structure of the test is seen a very con- 
spicuous difference from Ech. esculentus , viz. that all the ambulacral 
plates bear a primary tubercle, while in esculentus only every 
second ambulacral plate bears a primary tubercle; only on the 
* 
oral side some few of the ambulacral plates lack the primary 
tubercle. The tubercles are somewhat smaller than usually in 
esculentus , especially the secondary tubercles are less prominent. 
The spines are green, not violet on the tip as is usually the case 
in esculentus. It is especially to be remarked that spines are 
