148 
shaped lobes, not supported by a skeletal rod. 1 ) (In 
Echinocardium larvæ with the posterolateral arms just beginning 
to develop and not larger than in the Brissopsis- larva, the sup- 
porting rod is already distinet, so that they are at once distinguish- 
able). The posterior process is short, hardly as long as the body, 
in marked distinetion from the exceedingly long posterior process 
of the Spatangus larva. (In the Echinocardium larva the posterior 
process varies very mueh in length, from about body length or 
somewhat more to quite a diminutive stump; this is not the result 
of absorption, 2 ) as it may be found so short in all different larval 
stages). 
The Brissopsis larva is considerably smaller than that of Echino¬ 
cardium cordatum; the colour is the usual: prominent red patches 
in the ends of the arms and scattered red pigment cells in the body. 
There is no yellow pigment. 
IV. Stichaster roseus (O. Fr. Muller) (?). 
Among the Asteroid larvæ observed at Kristineberg was a form 
which could hardly be identified with any of those previously de- 
scribed (Fig. 3). The faet that it is in beginning metamorphosis 
shows that it is not a young stage of an Asterias larva to develop 
later into a Brachiolaria form. It is characterized by its processes, 
which are short, but very contractile and movable like those of 
the Asterias larva. The dorsal and ventral median processes are 
both well developed and of about equal length; there are no brach- 
iolarian processes and no suctorial disk. All the processes are yel- 
*) The same character is found in a Spatangoid larva, which I have from 
the Gulf of Panama. Further the Spatangoid larva figured by Metsch- 
n i k o f f (Studien fiber die Entwickelung d. Echinod. u. Nemertinen. Mém. 
Acad. Imp. St.-Pétersbourg. 7 Sér. XIV. 1869. Taf. VIII) appears to have 
no postero-lateral arms, not even the small lobes of the skin found in 
the Brissopsis- larva. Metschnikoff refers his larva to Schizaster 
canaliferus. (Cf. Th. Mortensen. Echinodermen-Larven d. Plankton- 
Exped. p. 107). 
2 ) This appears to be the meaning of MacBride (The development of 
Echinocardium cordatum. Part. I. p. 480\ 
