. Ascidians from the coasts of Canada [microform]. Sea squirts; Tunicata; Ascidies (Tuniciers); Tuniciers. II h IV'' 'i>i: ii6 Transactions of the Canadian Institute. [vol. ix at some distance from the atrial siphon, where the current is not as great and as a result the eggs are usually retained. This retention of the eggs may be quite constant in a genus, may be characteristic of certain species only of a genus, or may occur only in occasional individuals of a species. In some cases the eggs are, though retained, laid in lots, so that practically only one stage can be obtained from one ind
. Ascidians from the coasts of Canada [microform]. Sea squirts; Tunicata; Ascidies (Tuniciers); Tuniciers. II h IV'' 'i>i: ii6 Transactions of the Canadian Institute. [vol. ix at some distance from the atrial siphon, where the current is not as great and as a result the eggs are usually retained. This retention of the eggs may be quite constant in a genus, may be characteristic of certain species only of a genus, or may occur only in occasional individuals of a species. In some cases the eggs are, though retained, laid in lots, so that practically only one stage can be obtained from one individual and all the individuals of one locality may have their eggs at the same stage of development. The following is a list of the simple forms of the stations that retain their eggs:— Genera,—Dendrodoa, eggs produced continuously. KateUropa " " " Species,—Caesira cooperi, eggs produced continuously. C. canadensis, " , Occasional individuals of Ascidiopsis prunum, eggs produced in lots. CortUainflata, BoUenia kirsuta, (?) Yotmg individuals, for studying the post-larval development, can be obtained in the case of the commoner species by carefully examining the free surface in individuals of those species which have a roughened test. Individuals, that were anaesthetized with cocaine, killed in the extended condition and well fixed, have furnished me with an abundance of stages of some of the commoner species. A series of sections made of an adult Dendrodoa cameo, yielded in addition, (i) an almost complete series of stages of the same species from the fertilized egg up to the free-swimming larvae, (a) a 'young adult' of the same species, (3) two 'young adulu' of Ascidiopsis prunum and (4) a' young adult' of some species of Caesira! As is well known, the Asddians harbour many commensals. Pro- tosoa are to be found in the pharynx and atrial cavity in many of the simple forms of both coasts, the majority being attached to the oral tentacles. Va
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